feat: enhance conversation event logs and update related data structures

[chenyme]

Summary

异常对话仅出现在“对话事件”日志中，但此前缺少上游路由信息，管理员无法定位产生异常的上游渠道。

本次通过事件的 runID 批量关联运行快照，为对话事件补充上游名称、平台模型、真实模型、绑定编码和协议，并在管理后台列表及详情中展示。路由前发生的异常保持为空，不推测上游来源。

Change type

• Bug fix
• Feature
• Documentation
• Refactor
• Configuration / deployment
• Security hardening
• Other

Affected areas

• Frontend / UI
• Backend / API
• Authentication / authorization
• Conversations / streaming
• Files / RAG / extraction
• Model routing / providers
• MCP / tools
• Billing / payments
• Admin console
• Deployment / Docker / configuration
• Documentation

Verification

• cd backend && go test ./...
• cd frontend && pnpm lint
• cd frontend && pnpm exec tsc --noEmit
• git diff --check
• Frontend build not run; static checks and type checking were used for this change.

Screenshots, API examples, or logs

The admin conversation event response now additionally includes:

{
  "providerProtocol": "openai_responses",
  "upstreamName": "OpenAI Official",
  "platformModelName": "gpt-5.5",
  "routedBindingCode": "binding_openai",
  "upstreamModelName": "gpt-5.5-pro"
}

Configuration, migration, and compatibility notes

• No database migration or configuration change is required.
• The admin conversation events API only adds response fields and remains backward compatible.
• Route snapshots are loaded in one batch per event page to avoid N+1 queries.
• Events produced before route resolution return empty route fields.
• Generated Swagger definitions were updated.

Documentation

• Documentation is not needed for this change.
• Documentation was updated.
• Documentation still needs to be updated.

Security and privacy

• No secrets, tokens, credentials, local config, or personal data are included.
• User data access remains scoped by authenticated user context unless an admin-only path explicitly requires broader access.
• Security-sensitive behavior was reviewed, including authentication, authorization, provider routing, file processing, billing, and admin APIs where relevant.

Upstream route details are exposed only through the existing administrator-only logs API.

Checklist

• I searched existing issues and pull requests.
• Changes are focused and do not include unrelated refactors.
• Tests or static verification were run where practical.
• User-facing behavior, deployment steps, API contracts, or configuration changes are documented.
• Generated artifacts are included only when this project explicitly requires them.
• Caches, build output, .pyc files, .env files, and local storage data are not committed.