fix(skills): honor policy table for dangerous verdicts

Salvaged from PR #1007 by stablegenius49.

- let INSTALL_POLICY decide dangerous verdict handling for builtin skills
- allow --force to override blocked dangerous decisions for trusted and community sources
- accept --yes / -y as aliases for --force in /skills install
- update regression tests to match the intended policy precedence

tests/hermes_cli/test_skills_hub.py

@@ -3,7 +3,7 @@ from io import StringIO
 import pytest
 from rich.console import Console
 
-from hermes_cli.skills_hub import do_check, do_list, do_update
+from hermes_cli.skills_hub import do_check, do_list, do_update, handle_skills_slash
 
 
 class _DummyLockFile: