feat(gateway): MosaicPlugin lifecycle + ReloadService + hot reload (P8-013) (#182)

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

apps/gateway/src/chat/chat.gateway.ts

@@ -12,7 +12,7 @@ import {
 import { Server, Socket } from 'socket.io';
 import type { AgentSessionEvent } from '@mariozechner/pi-coding-agent';
 import type { Auth } from '@mosaic/auth';
-import type { SetThinkingPayload, SlashCommandPayload } from '@mosaic/types';
+import type { SetThinkingPayload, SlashCommandPayload, SystemReloadPayload } from '@mosaic/types';
 import { AgentService } from '../agent/agent.service.js';
 import { AUTH } from '../auth/auth.tokens.js';
 import { CommandRegistryService } from '../commands/command-registry.service.js';
@@ -203,6 +203,11 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
     client.emit('command:result', result);
   }
 
+  broadcastReload(payload: SystemReloadPayload): void {
+    this.server.emit('system:reload', payload);
+    this.logger.log('Broadcasted system:reload to all connected clients');
+  }
+
   private relayEvent(client: Socket, conversationId: string, event: AgentSessionEvent): void {
     if (!client.connected) {
       this.logger.warn(