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/e2e/page-title.spec.ts

@@ -0,0 +1,67 @@
+import { test, expect, type Page } from '@playwright/test';
+
+// Guards the title-on-nav behavior: without this, a stale title from
+// the last manga / author page lingers when the user navigates to a
+// generic page like /upload.
+
+async function mockAnonymous(page: Page) {
+    await page.route('**/api/v1/auth/config', async (route) => {
+        await route.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ self_register_enabled: true, private_mode: false })
+        });
+    });
+    await page.route('**/api/v1/auth/me', async (route) => {
+        await route.fulfill({
+            status: 401,
+            contentType: 'application/json',
+            body: JSON.stringify({ error: { code: 'unauthenticated', message: 'unauthenticated' } })
+        });
+    });
+    await page.route('**/api/v1/mangas*', async (route) => {
+        await route.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ items: [], page: { limit: 50, offset: 0, total: 0 } })
+        });
+    });
+}
+
+test('static route titles use the brand-first layout map', async ({ page }) => {
+    await mockAnonymous(page);
+
+    await page.goto('/');
+    await expect(page).toHaveTitle('Mangalord');
+
+    await page.goto('/upload');
+    await expect(page).toHaveTitle('Mangalord | Upload');
+
+    await page.goto('/login');
+    await expect(page).toHaveTitle('Mangalord | Login');
+
+    await page.goto('/bookmarks');
+    await expect(page).toHaveTitle('Mangalord | Bookmarks');
+
+    await page.goto('/collections');
+    await expect(page).toHaveTitle('Mangalord | Collections');
+});
+
+test('title updates when navigating away from a content page', async ({ page }) => {
+    await mockAnonymous(page);
+
+    // Pretend we just left a manga detail page — the document title
+    // would have been overridden to "Mangalord | Berserk". Use evaluate
+    // to set it synthetically so we can assert the regression cleanly
+    // even though the dynamic page itself isn't mocked here.
+    await page.goto('/');
+    await page.evaluate(() => {
+        document.title = 'Mangalord | Berserk';
+    });
+    expect(await page.title()).toBe('Mangalord | Berserk');
+
+    // Client-side nav to /upload — the root layout must reassert its
+    // mapped title or the stale "Berserk" lingers.
+    await page.goto('/upload');
+    await expect(page).toHaveTitle('Mangalord | Upload');
+});