feat(offline): tier 2 phase 4 — per-row pending-sync indicators

A small cloud-upload glyph appears next to any row whose id has a
queued offline write (offline-created temp ids and pending edits both
count). Tooltip reads "Pending sync — will save when online". Renders
nothing during normal online operation so the list stays clean.

- DB: `watchPendingIds(domain)` streams the union of target_id and
  temp_id across the queue, scoped per domain.
- Per-domain Riverpod stream providers for notes / tasks / projects.
- New `PendingSyncBadge` widget — used by KnowledgeItemCard (both
  list and grid variants), `_ProjectCard`, and `_TaskRow` in the
  project workspace.

flutter analyze clean; 21 tests pass. Closes #147 — all four phases
of Tier 2 offline mode are in place.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/data/local/database.dart

@@ -573,6 +573,27 @@ class FabledDatabase extends _$FabledDatabase {
     );
     return query.watchSingle().map((row) => row.read<int>('c'));
   }
+
+  /// Watch the set of ids in [domain] that have a queued write (either a
+  /// `target_id` for an update/delete or a `temp_id` for an offline create).
+  /// Phase 4 — used by per-row pending-sync indicators in the list views.
+  Stream<Set<int>> watchPendingIds(String domain) {
+    final query = customSelect(
+      'SELECT target_id, temp_id FROM pending_writes WHERE domain = ?',
+      variables: [Variable.withString(domain)],
+      readsFrom: {pendingWrites},
+    );
+    return query.watch().map((rows) {
+      final ids = <int>{};
+      for (final r in rows) {
+        final t = r.read<int?>('target_id');
+        final tmp = r.read<int?>('temp_id');
+        if (t != null) ids.add(t);
+        if (tmp != null) ids.add(tmp);
+      }
+      return ids;
+    });
+  }
 }
 
 // ── Row ↔ model converters ──────────────────────────────────────────────────