feat: Improve vector visualization with static assets and fixes

- Extract CSS and JavaScript into separate static files
  - Created nextcloud_mcp_server/auth/static/vector-viz.css
  - Created nextcloud_mcp_server/auth/static/vector-viz.js
  - Updated templates to reference external assets

- Fix vector visualization issues:
  - Normalize vectors before PCA to match Qdrant's cosine distance
  - Add zero-norm and NaN detection/handling for large datasets
  - Enable responsive Plotly sizing (autosize + responsive config)
  - Widen plot area to full viewport width with minimized margins

- Improve visualization accuracy:
  - Query point now positioned correctly relative to documents
  - Handles 200+ points without JSON serialization errors
  - Full-width plot maximizes screen space utilization

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

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

README.md

@@ -133,6 +133,7 @@ This enables natural language queries and helps discover related content across
 - **[App Documentation](docs/)** - Notes, Calendar, Contacts, WebDAV, Deck, Cookbook, Tables
 - **[Document Processing](docs/configuration.md#document-processing)** - OCR and text extraction setup
 - **[Semantic Search Architecture](docs/semantic-search-architecture.md)** - Experimental vector search (Notes only, opt-in)
+- **[Vector Sync UI Guide](docs/user-guide/vector-sync-ui.md)** - Browser interface for semantic search visualization and testing
 
 ### Advanced Topics
 - **[OAuth Architecture](docs/oauth-architecture.md)** - How OAuth works (experimental)