feat(ai): add Z.AI GLM-5.3

[DomineYH]

Summary

• add glm-5.3 to the global and China Z.AI Coding Plan catalogs with a stable fallback until models.dev publishes it
• use Z.AI's documented 1M context, 128K output, and low/high/max reasoning-effort mapping
• make GLM-5.3 the default model for both Z.AI providers
• keep Coding Plan cost metadata at zero because the general GLM-5.3 API and rate card are not released

Official references:

• https://docs.z.ai/guides/llm/glm-5.3
• https://docs.z.ai/devpack/latest-model

Verification

• npx vitest --run test/openai-completions-tool-choice.test.ts — 49 passed
• npx vitest --run test/model-resolver.test.ts — 47 passed
• npm run check — passed
• npm run check:model-data — passed
• isolated source CLI: --list-models glm-5.3 listed zai/glm-5.3 and zai-coding-cn/glm-5.3 with 1M context and 131.1K output

QA note

The focused real CLI model-list smoke passed. Broader rpc-drive, cli-smoke, and mock-loop self-tests exceeded their fixed 45s/60s source-startup deadlines on this WSL workstation; they made no provider requests and preserved the real auth file.

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Summary by cubic

Adds GLM-5.3 to the Z.AI Coding Plan catalogs and makes it the default for zai and zai-coding-cn. Previously GLM-5.2 was default; GLM-5.3 uses Z.AI’s 1M context and 128K output and includes a stable fallback until models.dev lists it.

• Provides fallback glm-5.3 metadata (text-only, tool_call, reasoning) that models.dev overrides when available; maps thinking levels to reasoning_effort (off/minimal/low→low, medium/high→high, xhigh/max→max); keeps tool streaming and max_tokens.
• Regenerates Z.AI provider snapshots in ai and updates tests in ai; sets provider defaults and tests in coding-agent to glm-5.3.
• Leaves Coding Plan cost metadata at zero until Z.AI publishes GLM-5.3 pricing. No migration unless you relied on the glm-5.2 default.

^{Written for commit 8e77681. Summary will update on new commits.}

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[DomineYH]

All PR checks and focused local verification are green. This contributor account cannot enable auto-merge or merge into the upstream repository; maintainer merge is required.