feat: paginate list views, fix stale page titles, tidy admin filter bar

Bundle of small UI/UX fixes plus a build hygiene tweak.

* List pagination — Home (`/`) and `/authors/[id]` silently capped at
  the backend default of 50 with no UI to advance. New reusable
  `Pager.svelte` (Prev/Next + numbered with ellipsis), URL-synced
  `?page=N`, and filter/search/sort reset to page 1 so users aren't
  stranded on an out-of-range page. Count label now shows a range
  ("Showing 51–100 of 237").

* Stale page title — Pages without a `<svelte:head><title>` left the
  document title at whatever the last manga / author / collection page
  set it to. Move static-route titles into a route-id → title map in
  the root layout and invert every dynamic title to brand-first
  (`Mangalord | {X}`) for consistency.

* Admin filter bar — `/admin/mangas` search input had `flex: 1` and
  ballooned across the row, shoving the sync-state select + Search
  button to the far right. Cap at 24rem, vertical-align the row, and
  promote the previously aria-only "Sync state" label to visible text.

* Build hygiene — `backend/target` had grown to 68 GiB. Cleaned and
  added `[profile.dev] debug = "line-tables-only"` (and `[profile.test]`
  too) to cut future dev builds by ~50–70% while keeping line numbers
  in backtraces.

Also: configure vitest to resolve Svelte's browser entry so
`@testing-library/svelte` can mount components in jsdom — needed for
the new `Pager.svelte.test.ts`.

Bump 0.48.0 -> 0.49.1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/routes/+layout.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
     import { onMount, onDestroy } from 'svelte';
     import { goto } from '$app/navigation';
+    import { page } from '$app/stores';
     import { logout } from '$lib/api/auth';
     import { authConfig } from '$lib/auth-config.svelte';
     import { preferences } from '$lib/preferences.svelte';
@@ -18,6 +19,32 @@
     let loggingOut = $state(false);
     let headerEl: HTMLElement | undefined = $state();
 
+    // Static-route title map. Dynamic pages (manga / author / collection /
+    // chapter) override this via their own <svelte:head><title>, since the
+    // title depends on data the layout doesn't have. Routes omitted here
+    // (notably the dynamic ones) fall through to the bare brand and rely
+    // on the page to set the descriptive form.
+    const STATIC_TITLES: Record<string, string> = {
+        '/': 'Mangalord',
+        '/login': 'Mangalord | Login',
+        '/register': 'Mangalord | Register',
+        '/upload': 'Mangalord | Upload',
+        '/bookmarks': 'Mangalord | Bookmarks',
+        '/collections': 'Mangalord | Collections',
+        '/profile': 'Mangalord | Profile',
+        '/profile/account': 'Mangalord | Account',
+        '/profile/bookmarks': 'Mangalord | Bookmarks',
+        '/profile/collections': 'Mangalord | Collections',
+        '/profile/history': 'Mangalord | Reading history',
+        '/profile/preferences': 'Mangalord | Preferences',
+        '/admin': 'Mangalord | Admin',
+        '/admin/mangas': 'Mangalord | Admin · Mangas',
+        '/admin/users': 'Mangalord | Admin · Users',
+        '/admin/system': 'Mangalord | Admin · System'
+    };
+
+    const layoutTitle = $derived(STATIC_TITLES[$page.route?.id ?? ''] ?? 'Mangalord');
+
     // Seed authConfig from the universal layout load. $effect keeps
     // the store in sync if `data` is replaced by a subsequent layout
     // load (client-side nav). The first run also covers initial
@@ -78,6 +105,10 @@
     }
 </script>
 
+<svelte:head>
+    <title>{layoutTitle}</title>
+</svelte:head>
+
 <header bind:this={headerEl}>
     <nav aria-label="primary">
         <a class="brand" href="/">Mangalord</a>