Graph editor: unified card colors, keyboard focus, color picker button

- Unified graph node colors with card color system (shared localStorage)
- Added color picker palette button to node overlay toolbar
- Auto-focus graph container for keyboard shortcuts to work immediately
- Trap Tab key to prevent focus escaping to footer
- Added mandatory bundle rebuild note to CLAUDE.md files

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/CLAUDE.md

@@ -54,7 +54,7 @@ netstat -an | grep 8080
 - **Permission errors**: Ensure file permissions allow Python to execute
 
 #### Files that DON'T require restart:
-- Static files (`static/*.html`, `static/*.css`, `static/*.js`) - these are served directly
+- Static files (`static/*.html`, `static/*.css`, `static/*.js`) - but you **MUST rebuild the bundle** after changes: `cd server && npm run build`
 - Locale files (`static/locales/*.json`) - loaded by frontend
 - Documentation files (`*.md`)
 - Configuration files in `config/` if server supports hot-reload (check implementation)