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>

server/README.md

@@ -0,0 +1,52 @@
+# BadNote Server (Optional)
+
+This directory contains an **optional** Python/FastAPI backend. The BadNote desktop app does **not** depend on it.
+
+The Flutter client is local-first:
+
+- Notes and documents are stored in SQLite on device
+- OCR runs locally via Windows built-in OCR
+- Full-text search uses on-device FTS5
+
+## Why this exists
+
+This server was an early experiment for:
+
+- Multi-device note sync (push/pull)
+- Server-side OCR with EasyOCR
+- JWT authentication
+
+These features are **not wired into the current client**. The client previously had incomplete sync/OCR scaffolding that has been removed in favor of local processing.
+
+## Running (if you want to experiment)
+
+```bash
+cd server
+python -m venv .venv
+source .venv/bin/activate   # Windows: .venv\Scripts\activate
+pip install -r requirements.txt
+uvicorn badnote_server.main:app --host 0.0.0.0 --port 8080
+```
+
+API docs: http://localhost:8080/docs
+
+The OCR worker has heavy extra dependencies (EasyOCR + torch). Install them only
+if you want to run it:
+
+```bash
+pip install -r requirements-ocr.txt
+python -m badnote_server.ocr.worker
+```
+
+### Security notes
+
+- Set `BADNOTE_JWT_SECRET` in production. If unset, a secret is generated once
+  and persisted to `<data>/.jwt_secret` so tokens survive restarts.
+- Restrict origins with `BADNOTE_CORS_ORIGINS` (comma-separated). The default is
+  permissive (`*`, without credentials) for local development.
+
+## Status
+
+- Kept for reference and future optional sync work
+- Not part of the primary development path
+- No guarantee of API compatibility with future client versions