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/pages/executions/use-execution-search.ts

@@ -19,9 +19,11 @@ interface ExecutionSearchState {
   routeId: string;
   agentId: string;
   processorType: string;
+  live: boolean;
   offset: number;
   limit: number;
 
+  toggleLive: () => void;
   setStatus: (statuses: string[]) => void;
   toggleStatus: (s: string) => void;
   setTimeFrom: (v: string) => void;
@@ -47,9 +49,11 @@ export const useExecutionSearch = create<ExecutionSearchState>((set, get) => ({
   routeId: '',
   agentId: '',
   processorType: '',
+  live: true,
   offset: 0,
   limit: 25,
 
+  toggleLive: () => set((state) => ({ live: !state.live })),
   setStatus: (statuses) => set({ status: statuses, offset: 0 }),
   toggleStatus: (s) =>
     set((state) => ({