feat(#132): port MCP (Model Context Protocol) infrastructure

Implement MCP Phase 1 infrastructure for agent tool integration with
central hub, tool registry, and STDIO transport layers.

Components:
- McpHubService: Central registry for MCP server lifecycle
- StdioTransport: STDIO process communication with JSON-RPC 2.0
- ToolRegistryService: Tool catalog management
- McpController: REST API for MCP management

Endpoints:
- GET/POST /mcp/servers - List/register servers
- POST /mcp/servers/:id/start|stop - Lifecycle control
- DELETE /mcp/servers/:id - Unregister
- GET /mcp/tools - List tools
- POST /mcp/tools/:name/invoke - Invoke tool

Features:
- Full JSON-RPC 2.0 protocol support
- Process lifecycle management
- Buffered message parsing
- Type-safe with no explicit any types
- Proper cleanup on shutdown

Tests: 85 passing with 90.9% coverage

Fixes #132

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/mcp/mcp.module.ts

@@ -0,0 +1,15 @@
+import { Module } from "@nestjs/common";
+import { McpController } from "./mcp.controller";
+import { McpHubService } from "./mcp-hub.service";
+import { ToolRegistryService } from "./tool-registry.service";
+
+/**
+ * MCP (Model Context Protocol) Module
+ * Provides infrastructure for agent tool integration
+ */
+@Module({
+  controllers: [McpController],
+  providers: [McpHubService, ToolRegistryService],
+  exports: [McpHubService, ToolRegistryService],
+})
+export class McpModule {}