feat(think-mode): add GLM-4.7 thinking mode support

[sisyphus-dev-ai]

Summary

Add thinking mode support for Z.AI's GLM-4.7 model via the zai-coding-plan provider.

Changes

• Add zai-coding-plan to THINKING_CONFIGS with extra_body.thinking config format
• Add glm pattern to THINKING_CAPABLE_MODELS for model detection
• Add comprehensive tests for GLM thinking mode functionality

Technical Details

GLM-4.7 uses OpenAI-compatible API format with extra_body wrapper:

"zai-coding-plan": {
  providerOptions: {
    "zai-coding-plan": {
      extra_body: {
        thinking: {
          type: "enabled",
          clear_thinking: false,  // Preserved Thinking mode
        },
      },
    },
  },
}

Key points:

• thinking.type: "enabled" - Activates thinking mode
• thinking.clear_thinking: false - Preserves reasoning content in response (like Claude's <thinking> block)
• No HIGH_VARIANT_MAP entries needed since GLM-4.7 has thinking enabled by default

Testing

• All 54 switcher tests pass (including 7 new GLM tests)
• All 71 think-mode tests pass
• TypeScript type check passes
• Build succeeds

Closes #1030

---

Summary by cubic

Adds thinking mode support for Z.AI’s GLM-4.7 via the zai-coding-plan provider, preserving reasoning content in responses. Completes Linear #1030 by enabling GLM detection and configuration.

• New Features
  • Added zai-coding-plan entry to THINKING_CONFIGS with extra_body.thinking { type: "enabled", clear_thinking: false }.
  • Updated THINKING_CAPABLE_MODELS to detect GLM models via the "glm" pattern.
  • No high variant needed for GLM; getHighVariant returns null.
  • Added tests for GLM-4.7 and GLM-4.6v behavior and config structure.

^{Written for commit de6f4b2. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

[code-yeongyu]

@sisyphus-dev-ai i dont think you have references on the pr description - please investigate and update to have them on the description. ulw and if not you must update the code