feat(web): dashboard All Libraries view saves the global scope

The All Libraries entry in the library switcher could render the
cross-library dashboard but rejected its own settings: the modal
refused to open without a library ('Select a specific library...') and
a save sent library_id: '' (server 400). The server now stores a
global scope (separate table; null/absent library_id, empty string
still 400), so:

- openDashboardSettings allows the All view and fetches prefs without
  the library param (reads the global row; previously a loose NULL
  OR-clause matched an arbitrary library's row).
- saveDashboardSettings sends library_id: null from All Libraries.
- The settings modal gains a scope label (#dashboard-scope-label)
  showing which library — or All Libraries — a save will customize
  (user requirement: always know the scope).

Verified end-to-end in headless Chromium: reorder on All Libraries →
save (null) → reload → modal re-opens with the persisted order and the
All Libraries scope label; per-library save lands in its own row
without touching global (SQL-checked).

templates/dashboard.templ

@@ -172,6 +172,7 @@ templ DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections
 				<div>
 					<h2 class="text-xl font-bold" style="color: var(--text-primary)">Customize Dashboard</h2>
 					<p class="text-sm mt-1" style="color: var(--text-secondary)">Drag to reorder, toggle to show or hide.</p>
+					<p class="text-xs mt-1 font-medium" id="dashboard-scope-label" style="color: var(--accent)"></p>
 				</div>
 				<button data-action="close-dashboard-settings" class="icon-btn" aria-label="Close">
 					@Icon("close", "h-5 w-5")

templates/dashboard_templ.go

@@ -573,7 +573,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 			templ_7745c5c3_Var26 = templ.NopComponent
 		}
 		ctx = templ.ClearChildren(ctx)
-		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 51, "<div id=\"dashboard-settings-modal\" class=\"hidden fixed inset-0 z-[70] flex items-center justify-center p-4\" style=\"background-color: var(--surface-overlay);\"><div class=\"card p-6 w-full max-w-2xl shadow-2xl\" style=\"box-shadow: var(--shadow-pop);\"><div class=\"flex justify-between items-center mb-6\"><div><h2 class=\"text-xl font-bold\" style=\"color: var(--text-primary)\">Customize Dashboard</h2><p class=\"text-sm mt-1\" style=\"color: var(--text-secondary)\">Drag to reorder, toggle to show or hide.</p></div><button data-action=\"close-dashboard-settings\" class=\"icon-btn\" aria-label=\"Close\">")
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 51, "<div id=\"dashboard-settings-modal\" class=\"hidden fixed inset-0 z-[70] flex items-center justify-center p-4\" style=\"background-color: var(--surface-overlay);\"><div class=\"card p-6 w-full max-w-2xl shadow-2xl\" style=\"box-shadow: var(--shadow-pop);\"><div class=\"flex justify-between items-center mb-6\"><div><h2 class=\"text-xl font-bold\" style=\"color: var(--text-primary)\">Customize Dashboard</h2><p class=\"text-sm mt-1\" style=\"color: var(--text-secondary)\">Drag to reorder, toggle to show or hide.</p><p class=\"text-xs mt-1 font-medium\" id=\"dashboard-scope-label\" style=\"color: var(--accent)\"></p></div><button data-action=\"close-dashboard-settings\" class=\"icon-btn\" aria-label=\"Close\">")
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
@@ -593,7 +593,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 			var templ_7745c5c3_Var27 string
 			templ_7745c5c3_Var27, templ_7745c5c3_Err = templ.ResolveAttributeValue(section.ID)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 184, Col: 37}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 185, Col: 37}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var27)
 			if templ_7745c5c3_Err != nil {
@@ -606,7 +606,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 			var templ_7745c5c3_Var28 string
 			templ_7745c5c3_Var28, templ_7745c5c3_Err = templ.ResolveAttributeValue(fmt.Sprintf("%v", section.IsSystem))
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 185, Col: 58}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 186, Col: 58}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var28)
 			if templ_7745c5c3_Err != nil {
@@ -627,7 +627,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 			var templ_7745c5c3_Var29 string
 			templ_7745c5c3_Var29, templ_7745c5c3_Err = templ.JoinStringErrs(section.Icon)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 190, Col: 43}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 191, Col: 43}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var29))
 			if templ_7745c5c3_Err != nil {
@@ -640,7 +640,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 			var templ_7745c5c3_Var30 string
 			templ_7745c5c3_Var30, templ_7745c5c3_Err = templ.JoinStringErrs(section.Title)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 192, Col: 84}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 193, Col: 84}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var30))
 			if templ_7745c5c3_Err != nil {
@@ -668,7 +668,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 				var templ_7745c5c3_Var31 string
 				templ_7745c5c3_Var31, templ_7745c5c3_Err = templ.ResolveAttributeValue(section.ID)
 				if templ_7745c5c3_Err != nil {
-					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 202, Col: 42}
+					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 203, Col: 42}
 				}
 				_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var31)
 				if templ_7745c5c3_Err != nil {
@@ -701,7 +701,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 		var templ_7745c5c3_Var32 string
 		templ_7745c5c3_Var32, templ_7745c5c3_Err = templ.JoinStringErrs(itemsPerSection)
 		if templ_7745c5c3_Err != nil {
-			return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 228, Col: 128}
+			return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 229, Col: 128}
 		}
 		_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var32))
 		if templ_7745c5c3_Err != nil {
@@ -714,7 +714,7 @@ func DashboardSettingsModal(sections []handlers.SectionData, hiddenCollections [
 		var templ_7745c5c3_Var33 string
 		templ_7745c5c3_Var33, templ_7745c5c3_Err = templ.ResolveAttributeValue(itemsPerSection)
 		if templ_7745c5c3_Err != nil {
-			return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 235, Col: 28}
+			return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/dashboard.templ`, Line: 236, Col: 28}
 		}
 		_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var33)
 		if templ_7745c5c3_Err != nil {

web/src/dashboard.ts

@@ -20,14 +20,13 @@ async function openDashboardSettings(): Promise<void> {
   const librarySelect = document.getElementById(
     "library-select",
   ) as HTMLSelectElement;
-  const libraryId = librarySelect?.value;
+  const libraryId = librarySelect?.value || "";
-  if (!libraryId) {
-    showToast("Select a specific library to customize preferences", "error");
-    return;
-  }
 
+  // Empty select = the All Libraries view: its preferences are the GLOBAL
+  // scope — the server returns that row when library_id is absent.
+  const query = libraryId ? `?library_id=${encodeURIComponent(libraryId)}` : "";
   const response = await fetch(
-    `/api/dashboard/preferences?library_id=${libraryId}`,
+    `/api/dashboard/preferences${query}`,
     {
       headers: { Authorization: `Bearer ${localStorage.getItem("token")}` },
     },
@@ -36,6 +35,17 @@ async function openDashboardSettings(): Promise<void> {
   if (response.ok) {
     const prefs = await response.json();
     applyPreferencesToModal(prefs);
+    // Scope indicator: make it unmistakable what a save will customize.
+    const scopeEl = document.getElementById("dashboard-scope-label");
+    if (scopeEl) {
+      const optionText =
+        librarySelect?.selectedOptions[0]?.textContent || libraryId;
+      scopeEl.textContent = (
+        libraryId ? optionText : optionText || "All Libraries"
+      )
+        .replace(/\s*\(\d+\)$/, "")
+        .trim();
+    }
   } else {
     showToast("Failed to load library preferences", "error");
     console.error("API Error:", response.status, response.statusText);
@@ -142,7 +152,10 @@ async function saveDashboardSettings(): Promise<void> {
     ) as HTMLSelectElement;
     const libraryId = librarySelect?.value || "";
     const response = await apiPut("/dashboard/preferences", {
-      library_id: libraryId,
+      // Empty select = the All Libraries view: an explicit JSON null is
+      // the global scope (empty string is rejected by the server as a
+      // lost value — never a scope).
+      library_id: libraryId || null,
       hidden_collections: hiddenCollections,
       collection_order: collectionOrder,
       items_per_section: parseInt(itemsPerCollection),
@@ -150,10 +163,6 @@ async function saveDashboardSettings(): Promise<void> {
     if (response.ok) {
       showToast("Dashboard settings saved", "success");
       closeDashboardSettings();
-      if (!libraryId) {
-        showToast("Select a specific library to customize preferences", "error");
-        return;
-      }
       await fetchAndRenderSections(libraryId);
     }
   } catch (error) {