fix: add missing build facade and update gitignore to be more specific

- Change gitignore pattern from 'build/' to '/build/' to only ignore root build artifacts
- Add src/utils/build/index.ts focused facade that was accidentally gitignored
- This fixes CI build failures where files import from utils/build/index.ts

Author: cameroncooke

.gitignore

@@ -6,7 +6,7 @@ yarn-error.log*
 
 # TypeScript build output
 dist/
-build/
+/build/
 *.tsbuildinfo
 
 # Auto-generated files

src/utils/build/index.ts

@@ -0,0 +1 @@
+export { executeXcodeBuildCommand } from '../build-utils.ts';