[codex] fix verifier for current hook output

[leopardqween]

Summary

• update verifier banner assertions for the current activation hook output
• validate mode tracker reinforcement JSON instead of expecting silence
• keep the fix scoped to tests/verify_repo.py

Root Cause

The verifier still expected older hook behavior: an activation banner with a period and a silent mode tracker. The current hook emits a level-aware activation banner and structured UserPromptSubmit reinforcement context.

Verification

• python3 tests/verify_repo.py
• python3 -m unittest tests/test_hooks.py