feat(M4-013,M5-001,M5-002,M5-003): routing e2e tests, agent config loading, model+agent switching (#323)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/gateway/src/commands/command-executor-p8012.spec.ts

@@ -40,6 +40,7 @@ const mockRedis = {
   del: vi.fn(),
 };
 
+// Mock agent config returned by brain.agents.findByName for "my-agent-id"
 const mockAgentConfig = {
   id: 'my-agent-id',
   name: 'my-agent-id',
@@ -67,6 +68,10 @@ const mockBrain = {
   },
 };
 
+const mockChatGateway = {
+  broadcastSessionInfo: vi.fn(),
+};
+
 function buildService(): CommandExecutorService {
   return new CommandExecutorService(
     mockRegistry as never,
@@ -76,7 +81,7 @@ function buildService(): CommandExecutorService {
     mockRedis as never,
     mockBrain as never,
     null,
-    null,
+    mockChatGateway as never,
   );
 }