chore: apply oxlint fix-suggestions (unused imports + useless fragments)

Scoped to only `no-unused-vars` and `react/jsx-no-useless-fragment` —
the safe subset of --fix-suggestions. Primary changes:

- Remove unused named imports from statements
- Remove unused default/type imports entirely
- Collapse `<><Single/></>` fragments to `<Single/>`

Verified clean: typecheck + format + lint all green.

packages/server/src/utils/checkout-git.ts

@@ -710,7 +710,7 @@ function isGitError(error: unknown): boolean {
 async function requireGitRepo(cwd: string): Promise<void> {
   try {
     await runGitCommand(["rev-parse", "--git-dir"], { cwd, env: READ_ONLY_GIT_ENV });
-  } catch (error) {
+  } catch {
     throw new NotGitRepoError(cwd);
   }
 }