fix: handle None skills config in skills_config helpers

[Kailigithub]

When skills is set to None in config.yaml, get_disabled_skills() crashes with AttributeError: 'NoneType' object has no attribute 'get', and save_disabled_skills() would overwrite the key with a dict without preserving the user's intent.

Changes:

• get_disabled_skills: use or {} / or [] guards so None is treated the same as an absent key
• save_disabled_skills: replace config.setdefault("skills", {}) with an isinstance check so a non-dict value (including None) is replaced rather than silently kept

All 28 existing tests in test_skills_config.py pass; web-server skill endpoint tests also pass.

Closes #15486

[alt-glitch]

Duplicate of #13078 — both fix get_disabled_skills() crashing on None/null skills config. #13078 also addresses the scalar-splits-into-characters case from #13026.

[alt-glitch]

Duplicate of #13078

[teknium1]

Thanks for the null-config hardening work. This is an automated hermes-sweeper review; the reported behavior is now implemented on current main.

• PR fix(cli): get_disabled_skills handles null and scalar skills config (#13026) #61797 merged as 4c03032a240a297ce6603bf352cf76d88f59d75f and normalizes skills: null, null disabled values, scalar values, and non-dict sections in hermes_cli/skills_config.py:27-61.
• Regression coverage for null and scalar shapes is present in tests/hermes_cli/test_skills_config.py:49-75.
• The prior maintainer discussion correctly identified this as overlapping fix(skills_config): handle null/scalar values in get_disabled_skills #13078; fix(skills_config): handle null/scalar values in get_disabled_skills #13078 was subsequently closed with the note that the fix landed via fix(cli): get_disabled_skills handles null and scalar skills config (#13026) #61797.
• Current config loading also ignores a null override for a default mapping (hermes_cli/config.py:6262-6273), so active CLI/dashboard save callers receive a mapping rather than skills=None.

The PR’s getter hunk predates the current global-plus-platform union semantics, so it should not be applied over main.