feat: 版本轨道按分支彻底分开，自测分支不再共用 feature 轨

每个分支各有一条独立轨道（轨道名即分支名，master/main 沿用历史名 release），
轨道类型 kind 只决定构建号行为：release 上架自增、feature 自测不自增。

- branch_track 映射分支 → 轨道名，新增分支自动建同名轨道
- 迁移：旧的共用 release / feature 轨按分支拆开并复制已用构建号，
  拆完没有分支引用的旧共用轨直接删除；无自测分支时保留 feature 轨作模板
- 分支管理页的下拉只改轨道类型（是否自增），不再影响版本号归属
- 打包设置页按分支分块填写版本号

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BJaZ913U5GVdTkYHiRpvDU

config.example.json

@@ -47,7 +47,7 @@
     }
   },
   "next_app_id_prefix": 3,
-  "branches": ["master", "develop"],
+  "branches": ["master", "develop", "feature/示例分支"],
   "upload": {
     "mode": "webdav",
     "oss": {
@@ -76,8 +76,12 @@
     "tracks": {
       "release": { "kind": "release", "app_ver": "2.180.0", "build_map": {} },
       "develop": { "kind": "release", "app_ver": "2.180.0", "build_map": {} },
-      "feature": { "kind": "feature", "app_ver": "2.180.0", "build_map": {} }
+      "feature/示例分支": { "kind": "feature", "app_ver": "2.180.0", "build_map": {} }
     }
   },
-  "branch_track": { "master": "release", "develop": "develop" }
+  "branch_track": {
+    "master": "release",
+    "develop": "develop",
+    "feature/示例分支": "feature/示例分支"
+  }
 }