@

docs: reorganize api docs into categorized subdirectories and fill missing docs

- Categorize 77 existing api docs into 16 business-domain subdirectories
  (auth/ad/wallet/coupon/compare/savings/signin/tasks/invite/user/
   device/platform/intent/meituan/other) plus admin/ and internal/
- Split admin/ into 7 sub-resource subdirectories (auth/users/wallet/
  withdraws/feedbacks/admins/ad) with 4 single-file docs at root
- Create 21 new docs covering 28 previously undocumented endpoints:
  ad/watch-report, wallet/transfer-auth (3 endpoints), coupon/session+
  stats+completed-today+prompt (7), invite/me+invitees+bind+landing-track,
  user/onboarding (2), platform/flags+ad-config+app-version,
  intent/step+precoupon/step, analytics/events, order/report,
  report/submit+records, feedback/config+records, trace/finalize
- Add mock request/response JSON examples to all new docs
- Create docs/README.md with full category index for LLM navigation
- Update docs/api/README.md: fix all links, add new endpoint rows,
  replace "no doc" markers with actual links
- Fix back-navigation links (./README.md -> ../README.md or
  ../../README.md) in all moved files
@

docs/api/wallet/wallet-bind-wechat.md

@@ -0,0 +1,28 @@
+# POST /api/v1/wallet/bind-wechat — 微信授权 code 换 openid 并绑定
+
+> 所属:Wallet 组（前缀 `/api/v1/wallet`） | 鉴权:Bearer | 限流:同 IP ≤10 次/分 | [← 返回 API 索引](../README.md)
+>
+> 集成实现:见 [integrations/wxpay](../integrations/wxpay.md)（code 换 openid / userinfo）。
+
+## 入参
+
+| 字段 | 类型 | 必填 | 说明 |
+|---|---|---|---|
+| `code` | string | ✅ | 微信授权返回的 code（客户端 OAuth 拿到） |
+
+## 出参
+响应 `200`:`BindWechatResultOut`
+
+| 字段 | 类型 | 说明 |
+|---|---|---|
+| `bound` | bool | 固定 `true` |
+| `wechat_nickname` | string \| null | 微信昵称 |
+| `wechat_avatar_url` | string \| null | 微信头像 URL |
+
+## 错误码
+- `400` code 无效 / 换 openid 失败
+- `409` 该微信已绑定其他账号
+- `503` 微信支付未配置（`wxpay_configured=false`）
+
+## 说明
+后端用 `code` 调微信 `jscode2session`（或 OAuth）换 `openid` 并写入 user。提现前置:必须先绑定。`openid` 全局唯一（DB 唯一约束），一个微信只能绑一个账号。