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/Dockerfile

@@ -5,6 +5,9 @@ COPY package.json package-lock.json ./
 RUN npm ci
 
 COPY . .
+
+ARG VITE_ENV_NAME=PRODUCTION
+ENV VITE_ENV_NAME=$VITE_ENV_NAME
 RUN npm run build
 
 FROM nginx:1.27-alpine