feat: multi-provider support — Anthropic + Ollama (P2-002) (#74)

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

apps/gateway/src/agent/agent.module.ts

@@ -1,9 +1,12 @@
 import { Global, Module } from '@nestjs/common';
 import { AgentService } from './agent.service.js';
+import { ProviderService } from './provider.service.js';
+import { ProvidersController } from './providers.controller.js';
 
 @Global()
 @Module({
-  providers: [AgentService],
-  exports: [AgentService],
+  providers: [ProviderService, AgentService],
+  controllers: [ProvidersController],
+  exports: [AgentService, ProviderService],
 })
 export class AgentModule {}