Clean up tracked artifacts and commit vitest config

Remove node_modules/ and tsconfig.tsbuildinfo from git tracking
(both already in .gitignore). Add vitest.config.js which was
missing from version control.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -1,3 +1,4 @@
 dist/
 node_modules/
-.env
+.env
+tsconfig.tsbuildinfo