Add live/paused toggle, env badge, remove topnav search, rename labels

- Add LIVE/PAUSED toggle button that auto-refreshes search results every 5s
- Source environment badge from VITE_ENV_NAME env var (defaults to DEV locally, PRODUCTION in Docker)
- Remove search trigger button from topnav (command palette still available via keyboard)
- Rename "Transaction Explorer" to "Route Explorer" and "Active Now" to "In-Flight"

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/api/queries/executions.ts

@@ -14,7 +14,7 @@ export function useExecutionStats() {
   });
 }
 
-export function useSearchExecutions(filters: SearchRequest) {
+export function useSearchExecutions(filters: SearchRequest, live = false) {
   return useQuery({
     queryKey: ['executions', 'search', filters],
     queryFn: async () => {
@@ -25,6 +25,7 @@ export function useSearchExecutions(filters: SearchRequest) {
       return data!;
     },
     placeholderData: (prev) => prev,
+    refetchInterval: live ? 5_000 : false,
   });
 }