chore(frontend): add frontend-specific .gitignore

Adds a dedicated .gitignore for the React/Vite/TypeScript frontend
covering node_modules, build output, TypeScript incremental build
info, test coverage, and environment files.

frontend/.gitignore

@@ -0,0 +1,40 @@
+# ─────────────────────────────────────────────
+#  frontend/.gitignore  (React / Vite / TypeScript)
+# ─────────────────────────────────────────────
+
+# Dependencies
+node_modules/
+.pnp
+.pnp.js
+
+# Build output
+dist/
+.vite/
+
+# TypeScript incremental build info
+*.tsbuildinfo
+
+# Testing
+coverage/
+.vitest/
+
+# Env
+.env
+.env.*
+!.env.example
+
+# Logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+*.log
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Editor
+.idea/
+*.iml