feat(api): enhance public APK endpoint to return semantic version from OTA bundle

The PublicLatestAPK endpoint now reads the expoConfig.json from the OTA bundle
to extract the actual semantic version (expo.version) instead of returning
the runtimeVersion as the version name. Falls back to runtimeVersion if
expoConfig.json is not available.

internal/service/update_service.go

@@ -88,6 +88,28 @@ func (s *UpdateService) GetLatestAPK() (*model.APKInfo, error) {
 	return s.store.GetLatestAPK()
 }
 
+// GetAPKVersionName 返回 APK 对应 runtimeVersion 的 OTA bundle 中的语义版本号。
+// 读取路径：<root>/<runtimeVersion>/android/expoConfig.json -> expo.version
+// 若 OTA bundle 尚未发布或 expoConfig.json 缺失，返回空字符串（调用方应兜底）。
+func (s *UpdateService) GetAPKVersionName(runtimeVersion string) string {
+	releasePath, err := s.store.LatestReleasePath(runtimeVersion, "android")
+	if err != nil {
+		return ""
+	}
+	cfg, err := s.store.ReadExpoConfig(releasePath)
+	if err != nil {
+		return ""
+	}
+	expo, ok := cfg["expo"].(map[string]any)
+	if !ok {
+		return ""
+	}
+	if v, ok := expo["version"].(string); ok {
+		return v
+	}
+	return ""
+}
+
 func (s *UpdateService) BuildManifestResponse(req ManifestRequest) (ManifestResponse, error) {
 	releasePath, err := s.store.LatestReleasePath(req.RuntimeVersion, req.Platform)
 	if err != nil {