fix: add from __future__ import annotations to workspace_manager.py

Fixes NameError: ToolInstance not defined at runtime because
type annotations are evaluated at class definition time.
Deferring annotation evaluation with __future__ annotations
keeps TYPE_CHECKING imports from causing runtime crashes.

Also includes ruff formatting cleanup on workspace-related files.

apps/api/tests/unit/test_git_service.py

@@ -21,7 +21,9 @@ class TestGitServiceClone:
         with patch(
             "asyncio.create_subprocess_exec", return_value=mock_proc
         ) as mock_exec:
-            await GitService.clone("https://github.com/test/repo.git", "main", "/tmp/ws")
+            await GitService.clone(
+                "https://github.com/test/repo.git", "main", "/tmp/ws"
+            )
 
         mock_exec.assert_called_once_with(
             "git",