Rebrand the entire application from "胡萝卜社区" (Carrot BBS) to "威友" (WithYou), including:

- Update app name, package name (skin.carrot.bbs → cn.qczlit.withyou), and bundle identifier
- Update API endpoints (bbs.littlelan.cn → withyou.littlelan.cn)
- Update URL scheme (carrotbbs:// → withyou://)
- Rename database from carrot_bbs to with_you
- Update CI/CD pipeline image names and artifact naming
- Add Android signing configuration for release builds
- Update all UI text and comments throughout the codebase
- Refactor registerStore to use in-memory state instead of AsyncStorage persistence
- Improve WebRTC track handling and call stream management
- Add metro platform resolution for native platform support

BREAKING app package, database, and URLs are no longer valid

src/screens/create/CreatePostScreen.tsx

@@ -1,6 +1,6 @@
-/**
+/**
  * 发帖页 CreatePostScreen（响应式适配）
- * 胡萝卜BBS - 发布新帖子
+ * 威友 - 发布新帖子
  * 参考微博发帖界面设计
  * 表单在宽屏下居中显示
  * 图片选择器在宽屏下显示更大的预览