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>

ios/.gitignore

@@ -0,0 +1,34 @@
+**/dgph
+*.mode1v3
+*.mode2v3
+*.moved-aside
+*.pbxuser
+*.perspectivev3
+**/*sync/
+.sconsign.dblite
+.tags*
+**/.vagrant/
+**/DerivedData/
+Icon?
+**/Pods/
+**/.symlinks/
+profile
+xcuserdata
+**/.generated/
+Flutter/App.framework
+Flutter/Flutter.framework
+Flutter/Flutter.podspec
+Flutter/Generated.xcconfig
+Flutter/ephemeral/
+Flutter/app.flx
+Flutter/app.zip
+Flutter/flutter_assets/
+Flutter/flutter_export_environment.sh
+ServiceDefinitions.json
+Runner/GeneratedPluginRegistrant.*
+
+# Exceptions to above rules.
+!default.mode1v3
+!default.mode2v3
+!default.pbxuser
+!default.perspectivev3