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>

.gitea/workflows/ci.yml

@@ -0,0 +1,101 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+# Allow builds to find SQLite / Flutter artifacts behind a corporate proxy.
+# Configure repo/org secrets HTTP_PROXY / HTTPS_PROXY in Gitea if needed.
+env:
+  FLUTTER_VERSION: "3.41.4"
+
+jobs:
+  analyze:
+    name: Analyze (Flutter)
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          flutter-version: ${{ env.FLUTTER_VERSION }}
+          channel: stable
+          cache: true
+
+      - name: Install dependencies
+        run: flutter pub get
+
+      - name: Verify formatting
+        run: dart format --output=none --set-exit-if-changed lib test
+
+      - name: Static analysis
+        run: flutter analyze
+
+  test:
+    name: Test (Flutter, Linux)
+    runs-on: ubuntu-latest
+    needs: analyze
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          flutter-version: ${{ env.FLUTTER_VERSION }}
+          channel: stable
+          cache: true
+
+      # The sqlite3 Dart package downloads a precompiled binary from GitHub
+      # releases when building native assets. On Linux CI we instead link the
+      # system libsqlite3 to avoid the download (faster + works offline).
+      # This override is applied only in CI; the committed pubspec.yaml stays
+      # clean so the Windows build downloads the bundled sqlite3.dll normally.
+      - name: Install system SQLite
+        run: sudo apt-get update && sudo apt-get install -y libsqlite3-dev
+
+      - name: Use system SQLite for native assets (CI only)
+        run: |
+          cat >> pubspec.yaml <<'EOF'
+
+          hooks:
+            user_defines:
+              sqlite3:
+                source: system
+          EOF
+
+      - name: Install dependencies
+        run: flutter pub get
+
+      - name: Run tests
+        run: flutter test --reporter expanded
+
+  server:
+    name: Test (Server, optional)
+    runs-on: ubuntu-latest
+    # The server is an optional/experimental backend. Keep it from blocking
+    # the pipeline, but still surface failures.
+    continue-on-error: true
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          cache: pip
+
+      - name: Install dependencies
+        working-directory: server
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+
+      - name: Run tests
+        working-directory: server
+        run: pytest -q