fix(manga): show force-resync result on mobile, not just desktop

`.resync-msg` (the admin Force-resync result) was display:none under 640px,
so mobile admins — who trigger resync from the overflow sheet — got no
success or error feedback. The element is already a sibling of `.action-row`
(not a child), so it survives the row being hidden; the only thing hiding it
was an explicit mobile rule. Drop that rule.

e2e: a mobile admin triggers Force resync from the overflow sheet and now
sees the "Metadata updated" result (written test-first against the hidden
element, then unhidden).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/e2e/mobile-manga-detail.spec.ts

@@ -236,6 +236,51 @@ test.describe('mobile manga detail', () => {
         await expect(sheet.getByTestId('overflow-add-to-collection')).toBeVisible();
     });
 
+    test('phone viewport: force resync from the overflow sheet surfaces a result message', async ({
+        page
+    }) => {
+        await mockDetail(page, { authed: true });
+        // Upgrade the session to admin so the Force resync action is offered.
+        // Registered after mockDetail so this auth/me wins (Playwright routes
+        // resolve most-recently-registered first).
+        await page.route('**/api/v1/auth/me', (route) =>
+            route.fulfill({
+                status: 200,
+                contentType: 'application/json',
+                body: JSON.stringify({
+                    user: {
+                        id: 'u1',
+                        username: 'admin',
+                        created_at: '2026-01-01T00:00:00Z',
+                        is_admin: true
+                    }
+                })
+            })
+        );
+        await page.route(`**/api/v1/admin/mangas/${mangaId}/resync`, (route) =>
+            route.fulfill({
+                status: 200,
+                contentType: 'application/json',
+                body: JSON.stringify({
+                    manga: mangaFixture(),
+                    cover_fetched: true,
+                    metadata_status: 'updated'
+                })
+            })
+        );
+        await page.setViewportSize(MOBILE);
+        await page.goto(`/manga/${mangaId}`);
+
+        await page.getByTestId('detail-overflow').click();
+        await page.getByTestId('overflow-force-resync').click();
+
+        // The result was previously display:none under 640px, leaving mobile
+        // admins with no feedback. It must now be visible.
+        const msg = page.getByTestId('force-resync-message');
+        await expect(msg).toBeVisible();
+        await expect(msg).toContainText(/Metadata updated/i);
+    });
+
     test('desktop viewport: mobile hero is hidden, existing layout + action-row stays', async ({
         page
     }) => {

frontend/src/routes/manga/[id]/+page.svelte

@@ -1243,9 +1243,9 @@
             display: none;
         }
 
-        .resync-msg {
-            display: none;
-        }
+        /* `.resync-msg` is a sibling of `.action-row`, not a child, so it
+           survives the row being hidden. Keep it visible on mobile: admins
+           trigger Force resync from the overflow sheet and need the result. */
 
         .continue {
             display: none;