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BREAKING app package, database, and URLs are no longer valid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/components/common/ImageGallery.tsx

@@ -218,7 +218,7 @@ export const ImageGallery: React.FC<ImageGalleryProps> = ({
       const allowedExts = ['jpg', 'jpeg', 'png', 'gif', 'webp'];
       const fileExt = allowedExts.includes(ext) ? ext : 'jpg';
 
-      const fileName = `carrot_${Date.now()}.${fileExt}`;
+      const fileName = `withyou_${Date.now()}.${fileExt}`;
       const destination = new File(Paths.cache, fileName);
 
       // File.downloadFileAsync 是新版 expo-file-system/next 的静态方法