补齐多端回归测试

[yeyixiang2007]

What to build

Add regression coverage for the shared contract and the mobile entry points so web, native app, and mini program changes do not silently break the core flows.
This slice should protect the newly introduced multi-platform boundaries with automated verification.

Acceptance criteria

• Shared API/type changes are covered by tests.
• Core home/search/detail/login flows have regression coverage for mobile entry points.
• Upload behavior is covered by tests where supported.

Blocked by

• 提取共享 API 和类型层 #234
• 打包 Android 和 iOS App 壳 #235
• 实现微信小程序核心 MVP #236
• 收敛移动端上传与文件能力 #237