feat(flutter): user-facing requests view + cancel (#356)

Closes the cleanest remaining #356 gap — Discover submits Lidarr
requests but had no surface for users to view or cancel their own.
Admin had it; user didn't.

- RequestsApi at lib/api/endpoints/requests.dart — listMine() +
  cancel(id). Same /api/requests endpoint the web /requests page
  uses; identical AdminRequest wire shape so the existing model
  is reused (just augmented with matched_*_id fields for the
  "Listen" CTA on completed rows).
- MyRequestsController mirrors the web's auto-poll (#369 piece
  already shipped server-side / web-side): 12s refresh while any
  row is mid-ingest (status='approved'), stops on settle. Riverpod
  Timer in build() that's cancelled in onDispose.
- RequestsScreen with kind/status pills, ingest progress copy,
  Cancel (with confirm dialog) and Listen CTAs per row state.
- Route /requests under the shell. Entry point in settings between
  Profile and Appearance — "My requests".
- Widget tests cover empty / pending / completed / rejected states +
  the Cancel-confirm dialog.

Out of scope this slice: Discover-screen "View your requests" CTA
after submitting a new request. Reasonable follow-up but doesn't
block the management loop.

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

flutter_client/lib/settings/settings_screen.dart

@@ -47,6 +47,8 @@ class SettingsScreen extends ConsumerWidget {
         children: const [
           _ProfileSection(),
           _Divider(),
+          _RequestsSection(),
+          _Divider(),
           _AppearanceSection(),
           _Divider(),
           StorageSection(),
@@ -94,6 +96,33 @@ class _SectionHeader extends StatelessWidget {
   }
 }
 
+class _RequestsSection extends StatelessWidget {
+  const _RequestsSection();
+
+  @override
+  Widget build(BuildContext context) {
+    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
+    return ListTile(
+      key: const Key('settings_requests_card'),
+      leading: Icon(Icons.queue_music, color: fs.parchment),
+      title: Text(
+        'My requests',
+        style: TextStyle(
+          color: fs.parchment,
+          fontFamily: 'Fraunces',
+          fontSize: 18,
+        ),
+      ),
+      subtitle: Text(
+        "Track what you've asked Minstrel to add",
+        style: TextStyle(color: fs.ash),
+      ),
+      trailing: Icon(Icons.chevron_right, color: fs.ash),
+      onTap: () => context.push('/requests'),
+    );
+  }
+}
+
 /// Renders an "Admin" entry only when the current profile has
 /// `is_admin = true`. Returns an empty SizedBox otherwise so the
 /// const-children layout above stays valid.