feat(ts): centralized library storage with cookie-based SSR support

- storage.ts: Centralize ALL_LIBRARIES = "__all__" sentinel constant.
  setSelectedLibrary() now writes both localStorage and a cookie
  (selectedLibrary, Path=/, SameSite=Lax, max-age=365d). The
  sentinel "__all__" is used in both storage mediums — empty strings
  are never stored. getSelectedLibrary() maps __all__ back to "".
  Cookie enables server-side rendering to read the stored library
  selection without access to localStorage.

- library-switcher.ts: Import ALL_LIBRARIES and setSelectedLibrary/
  getSelectedLibrary from storage.ts instead of managing localStorage
  directly. Remove local constants.

- dashboard.ts: Remove duplicate localStorage.setItem call that was
  overwriting the __all__ sentinel with raw empty string. Fix
  reloadPage() and scan-complete handler to work with empty libraryId.
  openDashboardSettings/saveDashboardSettings show clear messages for
  All Libraries mode.

- collections.ts: Remove library switcher initialization from the
  collections list page — the list page no longer has a switcher.

- series.ts: Rewrite to use initLibrarySwitcher from library-switcher
  module and switchWithTransition for navigation. Series card links
  no longer include library_id in their URLs.

- bookshelf.ts: Autocomplete fetch calls handle empty libraryId
  correctly for All Libraries mode.

- search.ts, collection-rules.ts: Use setSelectedLibrary() and
  getSelectedLibrary() from storage.ts instead of direct localStorage
  access.

web/src/dashboard.ts

@@ -21,7 +21,7 @@ async function openDashboardSettings(): Promise<void> {
   ) as HTMLSelectElement;
   const libraryId = librarySelect?.value;
   if (!libraryId) {
-    showToast("No library selected", "error");
+    showToast("Select a specific library to customize preferences", "error");
     return;
   }
 
@@ -95,8 +95,9 @@ function closeDashboardSettings(): void {
 }
 
 async function fetchAndRenderSections(libraryId: string): Promise<void> {
+  const param = libraryId ? `library_id=${libraryId}` : "";
   const response = await fetch(
-    `/api/dashboard/sections?library_id=${libraryId}`,
+    `/api/dashboard/sections?${param}`,
     {
       headers: {
         Authorization: `Bearer ${localStorage.getItem("token")}`,
@@ -107,7 +108,6 @@ async function fetchAndRenderSections(libraryId: string): Promise<void> {
   if (!response.ok) throw new Error("Failed to load sections");
   const data = await response.json();
   renderDashboardCollections(data.sections);
-  localStorage.setItem("selectedLibrary", libraryId);
 }
 
 async function saveDashboardSettings(): Promise<void> {
@@ -150,7 +150,7 @@ async function saveDashboardSettings(): Promise<void> {
       showToast("Dashboard settings saved", "success");
       closeDashboardSettings();
       if (!libraryId) {
-        showToast("Unable to refresh dashboard - no library selected", "error");
+        showToast("Select a specific library to customize preferences", "error");
         return;
       }
       await fetchAndRenderSections(libraryId);
@@ -302,12 +302,7 @@ async function reloadPage(): Promise<void> {
   const librarySelect = document.getElementById(
     "library-select",
   ) as HTMLSelectElement;
-  const libraryId = librarySelect?.value;
-
-  if (!libraryId) {
-    showToast("No library selected", "error");
-    return;
-  }
+  const libraryId = librarySelect?.value || "";
 
   await switchWithTransition("collections-container", () =>
     fetchAndRenderSections(libraryId),
@@ -444,13 +439,13 @@ function initDashboard() {
     const librarySelect = document.getElementById(
       "library-select",
     ) as HTMLSelectElement;
-    const libraryId = librarySelect?.value;
+    const libraryId = librarySelect?.value || "";
     console.log("[dashboard] libraryId:", libraryId);
-    if (!libraryId) return;
 
     try {
+      const param = libraryId ? `library_id=${libraryId}` : "";
       const response = await fetch(
-        `/api/dashboard/sections?library_id=${libraryId}`,
+        `/api/dashboard/sections?${param}`,
         {
           headers: {
             Authorization: `Bearer ${localStorage.getItem("token")}`,