feat(catalog): add Z.AI / Zhipu standard API and Coding Plan providers

[jimpablo]

Motivation

Zhipu / Z.AI only had a single Coding Plan-style entry. Split China and international, and standard API vs Coding Plan, so users can pick the endpoint that matches their key.

Changes

Adds four catalog providers (data only):

Provider	Region	Endpoint
zai	International	https://api.z.ai/api/paas/v4
zai-coding-plan	International	https://api.z.ai/api/coding/paas/v4
zhipu	China	https://open.bigmodel.cn/api/paas/v4
zhipu-coding-plan	China	https://open.bigmodel.cn/api/coding/paas/v4

• Models: glm-4.5-air, glm-4.7, glm-5-turbo, glm-5.1, glm-5v-turbo, glm-5.2 (default).
• glm-5.2 only: multi-level thinking (thinkingFormat = "deepseek", including xhigh); other models keep switch-only zai format.
• Costs follow Z.AI USD pricing on all four providers.
• Env keys: ZAI_API_KEY, ZAI_CODING_PLAN_API_KEY, ZHIPU_API_KEY, ZHIPU_CODING_PLAN_API_KEY.

Checks

• uv run pytest — 740 passed
• uv run ruff check . / ruff format --check . — clean
• uv run mypy — clean

Catalog-only change; no Python or architectural changes.