[codex] Add GLM-5.2 model support

[pingp76]

Summary

• Add a zhipuai_cn provider profile with GLM-5.2 defaults and ZhipuAI/BigModel key env support.
• Add a conservative glm-5.2 foundation model profile with long-context runtime policy defaults.
• Cover provider resolution, model profile matching, and runtime policy derivation in tests.
• Update doc/summary.md to reflect the new provider/profile and test counts.

Validation

• npm run typecheck
• npx vitest run src/llm-providers.test.ts src/foundation-models.test.ts src/runtime-policy.test.ts
• npx eslint src/llm-providers.ts src/foundation-models.ts src/llm-providers.test.ts src/foundation-models.test.ts src/runtime-policy.test.ts
• npm test
• git diff --check
• npx prettier --check src/llm-providers.ts src/foundation-models.ts src/llm-providers.test.ts src/foundation-models.test.ts src/runtime-policy.test.ts doc/summary.md