Model catalog: track independent coding provider candidates / 模型 catalog：跟踪独立 coding provider 候选

[zhnt]

Parent tracking issue: #101

Summary

Track independent coding-provider candidates for Chinese model vendors.

Provider IDs should follow the product/auth boundary. If a vendor's coding plan is a distinct product with separate credentials, billing, model namespace, or API documentation, it should be represented as a separate *-coding provider instead of being mixed into the main chat provider.

Scope

• For each core Chinese provider, check whether there is an independent coding product or coding plan.
• If a coding product has separate credentials, billing, model namespace, or API docs, create a dedicated provider issue such as <provider>-coding.
• If coding differs only by endpoint/protocol/region/lane under the same credentials, keep it under the main provider and use endpoint metadata such as lane: "coding".
• Keep this issue as a decision log and dispatch point, not as a bulk implementation issue.

Acceptance Criteria

• Each core provider has an explicit coding-product decision.
• Independent coding products are tracked as separate follow-up issues.
• Main provider issues do not mix independent coding product metadata into ordinary chat/reasoning providers.

中文摘要

跟踪中国模型厂商中可能需要独立 provider 的 coding 产品候选。

Provider ID 应按产品/账号/认证边界划分。如果某厂商的 coding plan 是独立产品，具备独立凭证、计费、模型命名空间或 API 文档，则应表示为单独的 *-coding provider，而不是混入主 chat provider。

范围

• 对每个核心中国 provider 检查是否存在独立 coding 产品或 coding plan。
• 如果 coding 产品具备独立凭证、计费、模型命名空间或 API 文档，则创建专门的 provider issue，例如 <provider>-coding。
• 如果 coding 只是在同一凭证体系下 endpoint/protocol/region/lane 不同，则仍放在主 provider 下，并使用 lane: "coding" 这类 endpoint metadata。
• 这个 issue 只作为决策记录和分发入口，不作为大批量实现 issue。

验收标准

• 每个核心 provider 都有明确的 coding 产品判断。
• 独立 coding 产品被拆成单独后续 issue。
• 主 provider issue 不混入独立 coding 产品 metadata。