Lock GLM bridge to Zhipu GLM-5.2

[yangfei222666-9]

Summary

• Lock the GLM smoke probe and candidate-review envelope to Zhipu GLM-5.2 only.
• Remove dynamic model and endpoint selection from the local bridge scripts.
• Remove non-Zhipu API-key environment fallbacks so the only accepted key source is ZHIPUAI_API_KEY.

Scope

Changed files:

• tools/glm52_smoke.py
• tools/glm52_candidate_review.py

Validation

Fresh local checks before push:

• python3 -m py_compile tools/glm52_smoke.py tools/glm52_candidate_review.py -> PASS
• GLM smoke dry-run -> provider_called=false, api_key_read=false
• candidate-review dry-run JSON check -> PASS
• dynamic --model / --endpoint rejection checks -> PASS
• static lock scan for removed fallback providers/envs/endpoints -> PASS

Boundaries

• No provider/API call was made.
• No API key was read or printed.
• This remains candidate bridge hardening until PR review/CI completes.
• This does not claim provider readiness, long-task readiness, or runtime readiness.