fix: auto-compute environment slug + respect environment filter globally

Part A: Environment creation slug is now auto-derived from display name
and shown read-only (matching app creation pattern). Removes manual slug
input.

Part B: All data queries now pass the selected environment to backend:
- Exchanges search, Dashboard L1/L2/L3 stats, Routes metrics, Route
  detail, correlation chains, and processor metrics all filter by
  selected environment.
- Backend RouteMetricsController now accepts environment parameter for
  both route and processor metrics endpoints.

Closes #XYZ

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/Routes/RoutesMetrics.tsx

@@ -15,6 +15,7 @@ import type { KpiItem, Column } from '@cameleer/design-system';
 import { useGlobalFilters } from '@cameleer/design-system';
 import { useRouteMetrics } from '../../api/queries/catalog';
 import { useExecutionStats, useStatsTimeseries } from '../../api/queries/executions';
+import { useEnvironmentStore } from '../../api/environment-store';
 import type { RouteMetrics } from '../../api/types';
 import styles from './RoutesMetrics.module.css';
 import tableStyles from '../../styles/table-section.module.css';
@@ -206,13 +207,14 @@ function buildKpiItems(
 export default function RoutesMetrics() {
   const { appId } = useParams();
   const navigate = useNavigate();
+  const selectedEnv = useEnvironmentStore((s) => s.environment);
   const { timeRange } = useGlobalFilters();
   const timeFrom = timeRange.start.toISOString();
   const timeTo = timeRange.end.toISOString();
 
-  const { data: metrics } = useRouteMetrics(timeFrom, timeTo, appId);
-  const { data: stats } = useExecutionStats(timeFrom, timeTo, undefined, appId);
-  const { data: timeseries } = useStatsTimeseries(timeFrom, timeTo, undefined, appId);
+  const { data: metrics } = useRouteMetrics(timeFrom, timeTo, appId, selectedEnv);
+  const { data: stats } = useExecutionStats(timeFrom, timeTo, undefined, appId, selectedEnv);
+  const { data: timeseries } = useStatsTimeseries(timeFrom, timeTo, undefined, appId, selectedEnv);
 
   // Map backend RouteMetrics[] to table rows
   const rows: RouteRow[] = useMemo(() =>