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>

.metadata

@@ -0,0 +1,45 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "ff37bef603469fb030f2b72995ab929ccfc227f0"
+  channel: "stable"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+    - platform: android
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+    - platform: ios
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+    - platform: linux
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+    - platform: macos
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+    - platform: web
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+    - platform: windows
+      create_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+      base_revision: ff37bef603469fb030f2b72995ab929ccfc227f0
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'