feat!: replace husky/lint-staged with lefthook v2

Migrate from husky + lint-staged to lefthook v2 for git hooks. Migrate
prettier config from CJS to ESM. Remove commitizen/cz-conventional-
changelog (release-please handles conventional commits).

prettier.config.mjs

@@ -0,0 +1,8 @@
+export default {
+  printWidth: 120,
+  tabWidth: 2,
+  useTabs: false,
+  semi: true,
+  singleQuote: true,
+  trailingComma: 'es5',
+};