Add .gitignore for standard project artifacts

Ignore node_modules, dist output, TypeScript build info,
environment files, editor configs, and OS metadata files.

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

.gitignore

@@ -0,0 +1,16 @@
+node_modules/
+dist/
+*.tsbuildinfo
+
+# Environment
+.env
+.env.*
+
+# Editor / OS
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+.DS_Store
+Thumbs.db