fix(web): scan progress — correct percentages, no layout shift, refresh-survivable

Bug: the admin 'Scanning Libraries' widget fed the server's 0-1
progress straight into percent strings and bar widths, so the overall
and per-library percentages capped at '1%' and the bars never filled.
Both now scale by 100 (matching the setup page, which was already
correct).

Bug: scan state only reached clients via websocket events, so a page
opened (or refreshed) mid-scan showed nothing until the next tick —
and the admin widget never re-attached at all. The worker now exposes
active jobs (with their library_id so rows keep their names), served
as GET /api/scanner/active (admin, re-attaches the widget + polling)
and GET /api/scanner/active-summary (any user, restores the sidebar
indicator on load). Idle hides both, exactly as before.

Annoyance: the sidebar's 'Scanning… N%' was a block element between
the logo and the nav, shoving every menu entry down while a scan ran.
The percent now lives inside the fixed-height logo row next to the
spinner (spinner last, so growing digits extend leftward); nothing
below it moves.

web/src/header.ts

@@ -41,6 +41,29 @@ const restoreLibrarySelection = (): void => {
 };
 
 const initializeScanListener = function (this: any) {
+  // Restore state on page load: a scan that started before this page
+  // was opened (or a refresh mid-scan) emits no websocket event until
+  // its next progress tick, so ask the server directly first.
+  const restoreActiveScan = async () => {
+    try {
+      const token = localStorage.getItem("token");
+      if (!token) return;
+      const resp = await fetch("/api/scanner/active-summary", {
+        headers: { Authorization: `Bearer ${token}` },
+      });
+      if (!resp.ok) return;
+      const data = await resp.json();
+      if (data.scanning) {
+        this.scanning = true;
+        this.scanProgress = Math.round((data.progress || 0) * 100);
+      }
+    } catch {
+      // Offline or endpoint unavailable — websocket events still drive
+      // the state once they arrive.
+    }
+  };
+  restoreActiveScan();
+
   const handler = (message: any) => {
     switch (message.type) {
       case "scan_progress":