feat: add environment filtering across all APIs and UI

Backend: Added optional `environment` query parameter to catalog,
search, stats, timeseries, punchcard, top-errors, logs, and agents
endpoints. ClickHouse queries filter by environment when specified
(literal SQL for AggregatingMergeTree, ? binds for raw tables).
StatsStore interface methods all accept environment parameter.

UI: Added EnvironmentSelector component (compact native select).
LayoutShell extracts distinct environments from agent data and
passes selected environment to catalog and agent queries via URL
search param (?env=). TopBar shows current environment label.

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

ui/src/api/queries/agents.ts

@@ -1,19 +1,27 @@
 import { useQuery } from '@tanstack/react-query';
-import { api } from '../client';
 import { config } from '../../config';
 import { useAuthStore } from '../../auth/auth-store';
 import { useRefreshInterval } from './use-refresh-interval';
 
-export function useAgents(status?: string, application?: string) {
+export function useAgents(status?: string, application?: string, environment?: string) {
   const refetchInterval = useRefreshInterval(10_000);
   return useQuery({
-    queryKey: ['agents', status, application],
+    queryKey: ['agents', status, application, environment],
     queryFn: async () => {
-      const { data, error } = await api.GET('/agents', {
-        params: { query: { ...(status ? { status } : {}), ...(application ? { application } : {}) } },
+      const token = useAuthStore.getState().accessToken;
+      const params = new URLSearchParams();
+      if (status) params.set('status', status);
+      if (application) params.set('application', application);
+      if (environment) params.set('environment', environment);
+      const qs = params.toString();
+      const res = await fetch(`${config.apiBaseUrl}/agents${qs ? `?${qs}` : ''}`, {
+        headers: {
+          Authorization: `Bearer ${token}`,
+          'X-Cameleer-Protocol-Version': '1',
+        },
       });
-      if (error) throw new Error('Failed to load agents');
-      return data!;
+      if (!res.ok) throw new Error('Failed to load agents');
+      return res.json();
     },
     refetchInterval,
   });