chore: add build outputs to gitignore

- packages/playground/dist/
- packages/vscode-extension/out/
- packages/vscode-extension/*.vsix

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

Author: kkratterf

.gitignore

@@ -29,3 +29,8 @@ package-lock.json
 # Environment
 .env
 .env.local
+
+# Build outputs
+packages/playground/dist/
+packages/vscode-extension/out/
+packages/vscode-extension/*.vsix