🐛 fix(playbook): import Optional for cli compatibility

restore the missing typing.Optional import in scripts/playbook.py
so older python runtimes can import the CLI module successfully.

add a regression test for typing annotation imports and register it
in the tests README.

scripts/playbook.py

@@ -6,6 +6,7 @@ from pathlib import Path
 from shutil import copy2, copytree, rmtree, which
 import subprocess
 import importlib.util
+from typing import Optional
 
 try:
     import tomllib

tests/README.md

@@ -14,6 +14,7 @@ tests/
 ├── test_firstparty_skills_quality.py # first-party skills 元数据与结构质量测试
 ├── test_gitattributes_modes.py     # gitattr_mode 行为测试
 ├── test_no_backup_flags.py         # no_backup 行为测试
+├── test_playbook_typing_imports.py # playbook.py typing 导入兼容性测试
 ├── test_sync_directory_actions.py  # sync_memory_bank/sync_prompts 行为测试
 ├── test_vendor_snapshot_templates.py # vendor 快照模板完整性测试
 ├── test_main_loop_cli.py           # main_loop CLI 测试

tests/test_playbook_typing_imports.py

@@ -0,0 +1,32 @@
+import ast
+import unittest
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+PLAYBOOK_SCRIPT = ROOT / "scripts" / "playbook.py"
+
+
+class PlaybookTypingImportTests(unittest.TestCase):
+    def test_optional_annotation_names_are_imported(self):
+        tree = ast.parse(PLAYBOOK_SCRIPT.read_text(encoding="utf-8"))
+
+        imported_names: set[str] = set()
+        referenced_names: set[str] = set()
+
+        for node in ast.walk(tree):
+            if isinstance(node, ast.Import):
+                for alias in node.names:
+                    imported_names.add(alias.asname or alias.name.split(".")[0])
+            elif isinstance(node, ast.ImportFrom):
+                for alias in node.names:
+                    imported_names.add(alias.asname or alias.name)
+            elif isinstance(node, ast.Name):
+                referenced_names.add(node.id)
+
+        if "Optional" in referenced_names:
+            self.assertIn("Optional", imported_names)
+
+
+if __name__ == "__main__":
+    unittest.main()