chore: add Biome for formatting and linting (#116)

- Add Biome as formatter and linter (replaces Prettier)
- Configure Husky + lint-staged for pre-commit hooks
- Add VS Code settings for format on save
- Ignore components/ui/ (shadcn generated code)
- Remove semicolons, use 4-space indent
- Reformat all files to new style

postcss.config.mjs

@@ -1,5 +1,5 @@
 const config = {
-  plugins: ["@tailwindcss/postcss"],
-};
+    plugins: ["@tailwindcss/postcss"],
+}
 
-export default config;
+export default config