fix: scope tsconfig to src/ so nest build emits dist/main.js

Without an include filter, tsc pulled in drizzle.config.ts from the
repo root too, which widened the inferred rootDir and nested output
under dist/src/main.js instead of dist/main.js -- crashing the
container (Cannot find module '/app/dist/main') since the Dockerfile
CMD expects the standard Nest layout.

tsconfig.json

@@ -16,5 +16,6 @@
     "strictNullChecks": true,
     "noImplicitAny": true,
     "esModuleInterop": true
-  }
+  },
+  "include": ["src/**/*.ts"]
 }