Remove tracked build artifacts, update .gitignore

.gitignore

@@ -2,10 +2,43 @@
 /lib/
 /test/
 custom-elements.json
-# top level source
-my-element.js
-my-element.js.map
-my-element.d.ts
-my-element.d.ts.map
-# only generated for size check
-my-element.bundled.js
+# Build outputs (generated — should not be tracked)
+/dist/
+/docs/
+
+# TypeScript incremental build cache
+*.tsbuildinfo
+
+# Vite cache
+.vite/
+
+# Logs
+*.log
+npm-debug.log*
+yarn-error.log*
+
+# macOS metadata
+.DS_Store
+.DS_Store?
+._*
+
+# Environment variables (never commit secrets)
+.env
+.env.local
+.env.*.local
+
+# Editor/IDE directories
+.vscode/
+.idea/
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+
+# Test coverage
+coverage/
+
+# Yarn
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml