chore(python): audit plugins shared modules

_managed_files owns the file snapshot reader and public metadata helpers used by pinned directories, durable copies, and opaque snapshots; transaction staging owns read_target and same_identity_and_contents; dead helpers removed; hook_template no longer re-exports the guard generator; mypy targets win32 so _windows_security type-checks.

Claude-Session: https://claude.ai/code/session_01Agoc9bRVE9KL7mmWtey9Vq

tests/test_guard_template.py

@@ -9,7 +9,7 @@ import sys
 from threading import Thread
 import time
 
-from elydora.plugins.hook_template import generate_guard_script
+from elydora.plugins.guard_template import generate_guard_script
 
 
 AGENT_ID = "agent 1"