feat: Redesign UI to match Nextcloud ecosystem aesthetic

This commit updates the web interface to better align with Nextcloud's
design system and improve the Vector Viz layout.

Changes:
- Replace emoji icons with Material Design SVG icons for better
  consistency with Nextcloud apps
- Simplify navigation styling with minimal padding and subtle active
  states (250px width)
- Update CSS variables to match Nextcloud design system
- Restructure Vector Viz from two-column to single-column vertical
  layout for better plot visibility
- Move search controls to compact horizontal grid at top
- Make navigation toggle always visible (not just on mobile)
- Fix plot container sizing with overflow:visible to prevent colorbar
  clipping
- Remove heavy shadows and custom card styling for cleaner aesthetic
- Add error and success page templates with consistent styling

Technical details:
- Preserve Alpine.js for reactive functionality
- Use CSS Grid for responsive horizontal controls layout
- Add smooth transitions for navigation collapse/expand
- Maintain HTMX for dynamic content loading

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

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

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="astrolabe.svg" alt="Nextcloud MCP Server" width="128" height="128">
+</p>
+
 # Nextcloud MCP Server
 
 [![Docker Image](https://img.shields.io/badge/docker-ghcr.io/cbcoutinho/nextcloud--mcp--server-blue)](https://github.com/cbcoutinho/nextcloud-mcp-server/pkgs/container/nextcloud-mcp-server)
@@ -29,6 +33,12 @@ docker run -p 127.0.0.1:8000:8000 --env-file .env --rm \
 
 # 3. Test the connection
 curl http://127.0.0.1:8000/health/ready
+
+# 4. Connect to the endpoint
+http://127.0.0.1:8000/sse
+
+# 4. Or with --transport streamable-http
+http://127.0.0.1:8000/mcp
 ```
 
 **Next Steps:**