feat: add API key spending quota

[g1331]

Summary

为 API Key 增加按金额限制的限额能力，支持与上游消费规则一致的时间窗口配置，并在超过额度时进行硬拒绝。

本次提交同时补上两类回归修复：

1. 保留 unbilled 请求的放行语义，避免在无法计费的场景中被额度短路拦截。
2. 将 API Key 创建、更新、删除后的 quota 状态同步改为尽力而为处理，避免数据库事务已经提交后因为后续同步失败而向调用方返回 500。

Related Issue

N/A

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (code improvement without changing functionality)
• Tests (adding or updating tests)
• Build/CI (changes to build system or CI configuration)

Changes

1. 新增 API Key 金额限额的数据结构、额度跟踪服务与管理接口字段，覆盖创建、编辑、展示与请求前校验。
2. 复用现有消费规则窗口语义，支持小时、天与滚动窗口等配置方式，并将超额场景统一处理为硬拒绝。
3. 在代理请求侧补充前置拒绝与计费判定衔接逻辑，仅对可明确计费的请求执行额度短路，保留 model_missing、usage_missing、price_not_found 等 unbilled 场景的既有行为。
4. 在 key manager 中为 create、update、delete 的 quota 状态同步增加回退逻辑，避免提交成功后的附加同步失败影响接口返回。
5. 补充管理端组件、API、转换器与服务层测试，覆盖额度配置、前置拒绝、unbilled 例外以及 post-commit best-effort 行为。

Test Plan

• Local tests pass (pnpm test:run)
• Type check passes (pnpm exec tsc --noEmit)
• Lint passes (pnpm lint)
• Manual testing completed

Checklist

• Code follows the project's coding standards
• Tests have been added where necessary
• Documentation has been updated (if applicable)
• Changes do not introduce security vulnerabilities
• Commit messages follow conventions

Screenshots

N/A

Additional Notes

pnpm test:run 已完整通过，结果为 2033 passed | 1 skipped。本 PR 已包含针对评审意见中两处行为回退的修复与对应回归测试。

[codecov]

Codecov Report

❌ Patch coverage is 59.14787% with 163 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.57%. Comparing base (278cf6b) to head (3ed4352).
⚠️ Report is 7 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #106      +/-   ##
==========================================
- Coverage   76.35%   75.57%   -0.79%     
==========================================
  Files          97       99       +2     
  Lines        6982     7319     +337     
  Branches     2438     2557     +119     
==========================================
+ Hits         5331     5531     +200     
- Misses        922      994      +72     
- Partials      729      794      +65     

Flag	Coverage Δ
typescript	75.57% <59.14%> (-0.79%)	⬇️

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