feat: Add dynamic Git-based versioning system

- Add app/version.py module generating version from Git metadata
- Format: YYYY.MM.DD+<commit_hash> (e.g., 2025.01.18+576c8ca9)
- Add +dirty suffix for uncommitted changes (ignores .env, technotes/)
- Add /api/version endpoint for monitoring
- Display version in hamburger menu
- Add freeze mechanism for Docker builds

Deploy command updated:
git push && ssh ... "cd ~/mc-webui && git pull && python -m app.version freeze && docker compose up -d --build"

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/main.py

@@ -12,6 +12,7 @@ from flask_socketio import SocketIO, emit
 from app.config import config, runtime_config
 from app.routes.views import views_bp
 from app.routes.api import api_bp
+from app.version import VERSION_STRING
 from app.archiver.manager import schedule_daily_archiving
 from app.meshcore.cli import fetch_device_name_from_bridge
 
@@ -43,6 +44,11 @@ def create_app():
     app.config['DEBUG'] = config.FLASK_DEBUG
     app.config['SECRET_KEY'] = 'mc-webui-secret-key-change-in-production'
 
+    # Inject version into all templates
+    @app.context_processor
+    def inject_version():
+        return {'version': VERSION_STRING}
+
     # Register blueprints
     app.register_blueprint(views_bp)
     app.register_blueprint(api_bp)