chore: add IDE and Git configuration

- Add VS Code workspace settings for consistent development experience
- Add VS Code extension recommendations (ESLint, Prettier, EditorConfig)
- Add .gitattributes to enforce LF line endings

.vscode/extensions.json

@@ -0,0 +1,7 @@
+{
+  "recommendations": [
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode",
+    "editorconfig.editorconfig"
+  ]
+}