feat: add webhook management UI and BeforeNodeDeletedEvent support

Added comprehensive webhook management capabilities including:

Webhook Client & API:
- Added WebhooksClient for Nextcloud webhooks API integration
- Create, list, update, and delete webhooks programmatically
- Support for event filters in webhook registration

Webhook Presets:
- Added preset system for common webhook configurations
- notes_sync: BeforeNodeDeletedEvent for Notes file operations
- calendar_sync: Calendar events (create, update, delete)
- deck_sync: Deck card operations
- files_sync: File system changes
- forms_sync: Form submissions (conditional)
- Filter presets by installed apps

Admin UI:
- Added multi-pane app view with tabs (User Info, Vector Sync, Webhooks)
- Webhooks tab for admin users only
- Enable/disable preset webhooks via UI
- View currently registered webhooks
- Uses htmx for dynamic loading and Alpine.js for tab state
- Admin permission checking via OCS API

CLI Improvements:
- Refactored CLI to separate module (cli.py)
- Updated entry point in pyproject.toml

BeforeNodeDeletedEvent Fix:
- Updated ADR-010 to document NodeDeletedEvent issue
- BeforeNodeDeletedEvent includes node.id before deletion
- NodeDeletedEvent lacks node.id (file already deleted)
- Implemented per Nextcloud maintainer recommendation

Testing:
- Added comprehensive webhook client tests
- Added webhook preset filtering tests
- Added admin permission tests

Configuration:
- Updated docker-compose.yml Qdrant settings

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

docker-compose.yml

@@ -94,7 +94,7 @@ services:
       # 1. Network mode: Set QDRANT_URL=http://qdrant:6333 (requires qdrant service)
       # 2. In-memory mode: Set QDRANT_LOCATION=:memory: (default if nothing set)
       # 3. Persistent local: Set QDRANT_LOCATION=/app/data/qdrant (stored in mcp-data volume)
-      - QDRANT_LOCATION=":memory:"  # In-memory mode for CI/testing (no external service required)
+      #- QDRANT_LOCATION=/app/data/qdrant  # In-memory mode used if not set
       #- QDRANT_URL=http://qdrant:6333  # Uncomment for network mode
       #- QDRANT_API_KEY=${QDRANT_API_KEY:-my_secret_api_key}  # Only for network mode