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/agent/agent.service.ts

@@ -352,6 +352,11 @@ export class AgentService implements OnModuleDestroy {
 
     this.sessions.set(sessionId, session);
     this.logger.log(`Agent session ${sessionId} ready (${providerName}/${modelId})`);
+    if (resolvedAgentName) {
+      this.logger.log(
+        `Agent session ${sessionId} using agent config "${resolvedAgentName}" (M5-001)`,
+      );
+    }
 
     return session;
   }