feat: enable proxy toggle on quick deploy, event log clearing, and UX fixes

- Add enable_proxy toggle to Quick Deploy form (defaults to on)
- Add DELETE /api/events/log/{id} and DELETE /api/events/log endpoints
- Add Clear All button with confirmation on Events page
- Rename "NPM Proxy" to "Enable Proxy" on stage form (provider-agnostic)
- Fix polling interval validation (min 60s) and number input trim errors
- Fix domain field no longer required in settings

internal/api/router.go

@@ -274,6 +274,10 @@ func (s *Server) Router() chi.Router {
 				// Config export (reveals project/infra details).
 				r.Get("/config/export", s.exportConfig)
 
+				// Event log management.
+				r.Delete("/events/log/{id}", s.deleteEvent)
+				r.Delete("/events/log", s.clearEvents)
+
 				// Auth management.
 				r.Get("/auth/settings", s.getAuthSettings)
 				r.Put("/auth/settings", s.updateAuthSettings)