feat: implement mcpd core server framework with Fastify

Add Fastify server with config validation (Zod), health/healthz endpoints,
auth middleware (Bearer token + session lookup), security plugins (CORS,
Helmet, rate limiting), error handler, audit logging, and graceful shutdown.
36 tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/mcpd/tsconfig.json

@@ -2,7 +2,8 @@
   "extends": "../../tsconfig.base.json",
   "compilerOptions": {
     "rootDir": "src",
-    "outDir": "dist"
+    "outDir": "dist",
+    "types": ["node"]
   },
   "include": ["src/**/*.ts"],
   "references": [