feat: 版本号按分支轨道分开管理，版本号配置收归管理员

master/develop 共用 release 轨（App_Store 打包构建号自增），feature 分支走
feature 轨（构建号永不自增，始终使用手填值），两条轨道的 App_Ver 各自独立。

- versions 改为 tracks 结构，旧的单轨/单值配置在加载时自动迁移进 release 轨
- 新增 config["branch_track"] 记录分支归属，缺省按分支名推断，可在分支管理页改
- 新增 PUT /api/config/branches/track；分支名含 / 时走请求体而非路径参数
- 修复 DELETE /api/config/branches/{name} 无法删除含 / 的分支（405）
- 版本号接口不再对普通用户开放，打包设置页整页改为管理员可见

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CLAUDE.md

@@ -25,11 +25,12 @@ FastAPI + Vue 3 iOS app auto-packaging service. Supports Ad_Hoc and App_Store bu
 - `backend/deps.py` — JWT auth dependency used by all protected routes
 - `backend/config.py` — loads .env, defines all config constants
 - `frontend/src/views/` — BuildView, HistoryView, ConfigView
-- `config.json` — runtime config (apps, schemes, servers, upload, branches) managed via web UI
+- `config.json` — runtime config (apps, schemes, servers, upload, branches, versions) managed via web UI
+- Versions are per-track: `release` (master/develop, build number auto-increments on App_Store) and `feature` (self-test, never increments); each branch's track lives in `config["branch_track"]`
 
 ## Conventions
 
 - All backend routes require JWT auth except `/api/auth/login` and `/api/health`
-- Admin-only routes: user management (`/api/users/*`)
+- Admin-only routes: user management (`/api/users/*`) and all of `/api/config/*` except `/api/config/apps*`
 - Config stored in `config.json` (apps/schemes/servers), `.env` (infra), SQLite `build_config` table (build settings)
 - Chinese UI and documentation throughout