feat(api): scaffold Fastify server with health route

- ESM Fastify 4 with Pino logger (pretty-print in dev only)
- Plugins: helmet, cors (allowlist via CORS_ORIGINS), rate-limit, sensible
- Zod-validated environment config in src/config/env.ts
- Modular structure under src/modules with /health route
- tsx watch for dev, tsc for build, dist/server.js as production entry

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "extends": "@ketopath/tsconfig/node.json",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src",
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["./src/*"]
+    },
+    "types": ["node"]
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}