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/authors/[id]/+page.svelte

@@ -1,15 +1,33 @@
 <script lang="ts">
     import MangaCard from '$lib/components/MangaCard.svelte';
+    import Pager from '$lib/components/Pager.svelte';
     import ArrowLeft from '@lucide/svelte/icons/arrow-left';
+    import { goto } from '$app/navigation';
+    import { page } from '$app/stores';
 
     let { data } = $props();
     const author = $derived(data.author);
     const mangas = $derived(data.mangas);
     const total = $derived(data.total);
+    const currentPage = $derived(data.currentPage);
+    const pageSize = $derived(data.pageSize);
+    const totalPages = $derived(
+        total != null && total > 0 ? Math.ceil(total / pageSize) : 1
+    );
+    const rangeStart = $derived(mangas.length === 0 ? 0 : (currentPage - 1) * pageSize + 1);
+    const rangeEnd = $derived((currentPage - 1) * pageSize + mangas.length);
+
+    function goToPage(p: number) {
+        if (p === currentPage) return;
+        const url = new URL($page.url);
+        if (p === 1) url.searchParams.delete('page');
+        else url.searchParams.set('page', String(p));
+        goto(url.pathname + url.search, { noScroll: false });
+    }
 </script>
 
 <svelte:head>
-    <title>{author.name} — Mangalord</title>
+    <title>Mangalord | {author.name}</title>
 </svelte:head>
 
 <nav class="back">
@@ -34,7 +52,7 @@
 {:else}
     {#if total != null}
         <p class="meta" data-testid="author-shown-of-total">
-            Showing {mangas.length} of {total}
+            Showing {rangeStart}–{rangeEnd} of {total}
         </p>
     {/if}
     <ul class="manga-grid" data-testid="author-manga-list">
@@ -42,6 +60,12 @@
             <MangaCard manga={m} testid={`author-manga-${m.id}`} />
         {/each}
     </ul>
+    <Pager
+        page={currentPage}
+        {totalPages}
+        onChange={goToPage}
+        testid="author-pager"
+    />
 {/if}
 
 <style>