fix: commands respect selected environment

Backend: AgentRegistryService gains findByApplicationAndEnvironment()
and environment-aware addGroupCommandWithReplies() overload.
AgentCommandController and ApplicationConfigController accept optional
environment query parameter. When set, commands only target agents in
that environment. Backward compatible — null means all environments.

Frontend: All command mutations (config update, route control, traced
processors, tap config, route recording) now pass selectedEnv to the
backend via query parameter.

Prevents cross-environment command leakage — e.g., updating config for
prod no longer pushes to dev agents.

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

ui/src/pages/Routes/RouteDetail.tsx

@@ -344,7 +344,7 @@ export default function RouteDetail() {
   function toggleRecording() {
     if (!config.data) return;
     const routeRecording = { ...config.data.routeRecording, [routeId!]: !isRecording };
-    updateConfig.mutate({ ...config.data, routeRecording });
+    updateConfig.mutate({ config: { ...config.data, routeRecording }, environment: selectedEnv });
   }
 
   // ── Derived data ───────────────────────────────────────────────────────────
@@ -545,14 +545,14 @@ export default function RouteDetail() {
     const taps = editingTap
       ? config.data.taps.map(t => t.tapId === editingTap.tapId ? tap : t)
       : [...(config.data.taps || []), tap];
-    updateConfig.mutate({ ...config.data, taps });
+    updateConfig.mutate({ config: { ...config.data, taps }, environment: selectedEnv });
     setTapModalOpen(false);
   }
 
   function deleteTap(tap: TapDefinition) {
     if (!config.data) return;
     const taps = config.data.taps.filter(t => t.tapId !== tap.tapId);
-    updateConfig.mutate({ ...config.data, taps });
+    updateConfig.mutate({ config: { ...config.data, taps }, environment: selectedEnv });
     setDeletingTap(null);
   }
 
@@ -561,7 +561,7 @@ export default function RouteDetail() {
     const taps = config.data.taps.map(t =>
       t.tapId === tap.tapId ? { ...t, enabled: !t.enabled } : t,
     );
-    updateConfig.mutate({ ...config.data, taps });
+    updateConfig.mutate({ config: { ...config.data, taps }, environment: selectedEnv });
   }
 
   function runTestExpression() {