fix: preserve dots in model names for OpenCode Zen and ZAI providers

[teknium1]

Summary

Fixes the HTTP 400 when using OpenCode Zen with dotted model names like minimax-m2.5-free, gpt-5.4, glm-5.1. The dot-to-hyphen conversion was applied to ALL models on Zen, but only Claude models need it.

Also fixes the same issue for ZAI provider (glm-5.1 was being mangled to glm-5-1).

Two-layer fix

Layer 1 (model_normalize.py): Remove opencode-zen from blanket _DOT_TO_HYPHEN_PROVIDERS. Add explicit mixed-mode block: Claude stays hyphenated (Zen's Claude endpoint uses anthropic_messages which expects claude-sonnet-4-6), all other models preserve dots.

Layer 2 (run_agent.py _anthropic_preserve_dots): Add opencode-zen and zai to provider allowlist. Broaden URL check from opencode.ai/zen/go to opencode.ai/zen/ to cover both Go and Zen endpoints. Add bigmodel.cn for ZAI URL detection.

Also adds glm-5.1 to ZAI model lists in models.py and setup.py.

Closes #7710

Test plan

• 136 tests pass across test_model_normalize.py, test_minimax_provider.py, test_model_validation.py
• New tests: Claude on Zen → hyphens, GLM/GPT/MiniMax/Kimi on Zen → dots preserved, ZAI → dots preserved, bigmodel.cn URL detection

Salvaged from 7 contributor PRs

Best aspects of each were combined:

PR	Author	What was used
#8708	@DomGrieco	Layer 1 mixed-mode approach (Claude hyphens, others dots)
#7739	@konsisumer	Layer 2 opencode-zen allowlist + URL broadening
#7719	@konsisumer	ZAI provider + bigmodel.cn URL + glm-5.1 model lists
#7296	@Esashiero	Identified the _DOT_TO_HYPHEN_PROVIDERS removal needed
#7497	@sharziki	Identified _MATCHING_PREFIX_STRIP as alternative category
#8750	@XiaoYingGee	Broader custom-proxy analysis (noted for future refactor)
#8752	@APTX4869-maker	Inverted logic analysis (noted for future refactor)
#7157	@kagura-agent	Custom base URL dot preservation analysis

[github-actions]

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Files:

hermes_cli/setup.py

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