feat: agent session management — metrics, channels, dispose (P2-006) (#78)

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

apps/gateway/src/agent/sessions.controller.ts

@@ -0,0 +1,39 @@
+import {
+  Controller,
+  Delete,
+  Get,
+  HttpCode,
+  HttpStatus,
+  NotFoundException,
+  Param,
+  UseGuards,
+} from '@nestjs/common';
+import { AuthGuard } from '../auth/auth.guard.js';
+import { AgentService } from './agent.service.js';
+
+@Controller('api/sessions')
+@UseGuards(AuthGuard)
+export class SessionsController {
+  constructor(private readonly agentService: AgentService) {}
+
+  @Get()
+  list() {
+    const sessions = this.agentService.listSessions();
+    return { sessions, total: sessions.length };
+  }
+
+  @Get(':id')
+  findOne(@Param('id') id: string) {
+    const info = this.agentService.getSessionInfo(id);
+    if (!info) throw new NotFoundException('Session not found');
+    return info;
+  }
+
+  @Delete(':id')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  async destroy(@Param('id') id: string) {
+    const info = this.agentService.getSessionInfo(id);
+    if (!info) throw new NotFoundException('Session not found');
+    await this.agentService.destroySession(id);
+  }
+}