fix: add baseUrl to tsconfig for path alias resolution in CI

tsc requires baseUrl to be set for paths mapping to work.
Without it, @/* path aliases are silently ignored during
standalone tsc --noEmit, causing TS2307 errors for
@/generated/prisma imports in CI.

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

tsconfig.json

@@ -18,6 +18,7 @@
         "name": "next"
       }
     ],
+    "baseUrl": ".",
     "paths": {
       "@/*": ["./src/*"]
     }