Handle expired GitLab auth errors

[legalverb]

Summary

• add shared handling for GitLab 401 responses so expired or invalid tokens show a clear recovery message
• route common requests and glab api JSON calls through helpers that avoid raw tracebacks/JSON parsing failures
• include both config-token and glab auth login recovery guidance for users

Verification

• python3 -m py_compile gitHappens.py ai_code_review.py
• git diff --check

Closes #73

Note: prepared transparently with AI assistance and manually verified before submission.