feat(ai-gateway): recommend GLM 5.2

[lambertjosh]

Summary

• Promote GLM 5.2 over GLM 5.1 in the normal recommended model list.
• Recommend GLM 5.2 for Z.AI Coding Plan BYOK users with its 1M-token context window.
• Add coverage ensuring GLM 5.2 remains in the recommended model configuration.

Verification

• Not manually tested; this is a model configuration-only change with no visual flow.

Visual Changes

N/A

Reviewer Notes

GLM 5.1 remains available through provider-synced model catalogs but is no longer recommended.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

Clean model promotion from GLM 5.1 to GLM 5.2 across provider config, model constants, and tests — all three files are consistently updated with no defects.

Files Reviewed (3 files)

• apps/web/src/lib/ai-gateway/providers/direct-byok/zai-coding.ts
• apps/web/src/lib/ai-gateway/providers/zai.ts
• apps/web/src/tests/openrouter-models-config.test.ts

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_{Reviewed by deepseek-v4-pro-20260423 · 237,823 tokens}

_{Review guidance: REVIEW.md from base branch main}