[ENHANCEMENT] Add support for GLM-5.1 via Z.ai provider

[akfrolov]

Problem (one or two sentences)

Roo Code has no support of newly released GLM-5.1 via GLM Coding Plan.

Context (who is affected and when)

All users who have Z.ai API and Coding plan subscriptions are not able to use glm-5.1 model in Roo.

Desired behavior (conceptual, not technical)

GLM-5.1 should be available among models in Z.ai provider.

Constraints / preferences (optional)

No response

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact

Roo Code Task Links (optional)

No response

Acceptance criteria (optional)

No response

Proposed approach (optional)

No response

Trade-offs / risks (optional)

No response

[roomote-v0]

I've analyzed this issue and here's my proposed implementation plan:

The codebase already has GLM-5 defined in the Z.ai provider. Adding GLM-5.1 follows the same pattern. The changes would be:

1. packages/types/src/providers/zai.ts - Add "glm-5.1" entry to both internationalZAiModels and mainlandZAiModels objects, modeled after GLM-5 (with thinking/reasoning support, ~202k context window). Pricing and exact specs would need to match the official Z.ai/BigModel docs for GLM-5.1.

2. src/api/providers/__tests__/zai.spec.ts - Add test cases for the new GLM-5.1 model in both international and China API line test suites, verifying model info is returned correctly (similar to existing GLM-4.7 and GLM-5 tests).

Questions before proceeding:

• Do you have the official GLM-5.1 pricing and context window specs? If not, I'll use the same values as GLM-5 as a starting point (202,752 context window, 16,384 max output tokens, same pricing tiers).
• Should GLM-5.1 support thinking/reasoning like GLM-5 does (with supportsReasoningEffort: ["disable", "medium"])?
• Does GLM-5.1 support vision (images), or is it text-only like GLM-5?

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.

[akfrolov]

It should be exactly as GLM-5. However, API is unavailable for now, GLM-5.1 is only active for GLM Coding Plan.