Fix bugs across app + server, optimize UI/UX, add Gitea CI

Bug fixes (Flutter):
- Wrap multi-statement DB writes (insert/update/delete note, deleteDocument,
  deletePageData, OCR FTS merge, migrations) in transactions to prevent data
  loss on interruption and a read-modify-write FTS race.
- Fix PdfDocument leaks on exception (try/finally dispose) and preserve image
  aspect ratio when stamping images onto PDF pages.
- Guard file-picker against empty selection (was .single -> crash).
- Fix eraser ConcurrentModificationError and unmodifiable-list crash on PDF
  pages; capture page synchronously on save to stop wrong-page data loss.
- Fix Riverpod DB-not-ready races, broken pull-to-refresh, settings load race,
  and search N+1; transform stored annotations on PDF page rotation.
- Normalize pen pressure for devices without a pressure range.
- PPT: single source of truth for slide strokes so ink displays and exports.

UI/UX:
- Material 3 typography, theme-aware colors (dark-mode fixes), hover cursors
  and right-click/visible actions on desktop, keyboard shortcuts (undo/redo/
  save/find), toolbar overflow handling, friendlier empty states, semantic OCR
  status badges, relative timestamps, 1-based page indicators, large-deck PPT
  navigation, and a scratchpad-scope label in split view.

Server (optional backend):
- Persist JWT secret (was per-process random), block path traversal in storage,
  fix CORS '*'+credentials, add OCR job ownership checks, last-writer-wins sync
  guard, constant-time login, and split out heavy OCR deps so the API/tests run
  without them.

CI: Gitea workflows for format+analyze+test (Linux, system sqlite) and a
Windows release build; pristine `flutter analyze`, all Flutter and server tests
green.

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

lib/providers/note_provider.dart

@@ -0,0 +1,68 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:uuid/uuid.dart';
+
+import '../models/note.dart';
+import '../services/database_service.dart';
+
+const _uuid = Uuid();
+
+final databaseServiceProvider = FutureProvider<DatabaseService>((ref) async {
+  return DatabaseService.getInstance();
+});
+
+final noteListProvider = AsyncNotifierProvider<NoteListNotifier, List<Note>>(
+  NoteListNotifier.new,
+);
+
+class NoteListNotifier extends AsyncNotifier<List<Note>> {
+  Future<DatabaseService> get _db => ref.read(databaseServiceProvider.future);
+
+  @override
+  Future<List<Note>> build() async {
+    final db = await _db;
+    return db.getAllNotes();
+  }
+
+  /// Reloads notes from the database and publishes the result to [state] so
+  /// the UI rebuilds. Used by pull-to-refresh.
+  Future<void> loadNotes() async {
+    state = const AsyncLoading();
+    state = await AsyncValue.guard(() async {
+      final db = await _db;
+      return db.getAllNotes();
+    });
+  }
+
+  Future<Note> createNote({String title = 'Untitled'}) async {
+    final db = await _db;
+    final now = DateTime.now();
+    final note = Note(
+      id: _uuid.v4(),
+      title: title,
+      createdAt: now,
+      updatedAt: now,
+    );
+    await db.insertNote(note);
+    state = AsyncData([note, ...state.value ?? []]);
+    return note;
+  }
+
+  Future<void> updateNote(Note note) async {
+    final db = await _db;
+    await db.updateNote(note);
+    final current = state.value ?? [];
+    state = AsyncData(current.map((n) => n.id == note.id ? note : n).toList());
+  }
+
+  Future<void> deleteNote(String id) async {
+    final db = await _db;
+    await db.deleteNote(id);
+    final current = state.value ?? [];
+    state = AsyncData(current.where((n) => n.id != id).toList());
+  }
+}
+
+final noteProvider = FutureProvider.family<Note?, String>((ref, id) async {
+  final db = await ref.watch(databaseServiceProvider.future);
+  return db.getNoteById(id);
+});