feat: add per-space timezone settings and improve booking management

- Add timezone configuration per space with fallback to system default
- Implement timezone-aware datetime display and editing across frontend
- Add migration for per_space_settings table
- Update booking service to handle timezone conversions properly
- Improve .gitignore to exclude build artifacts
- Add comprehensive testing documentation

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

frontend/vite.config.ts

@@ -12,6 +12,8 @@ export default defineConfig({
   },
   server: {
     port: 5173,
+    host: '0.0.0.0',
+    allowedHosts: ['claude-agent', 'localhost'],
     proxy: {
       '/api': {
         target: 'http://localhost:8000',