feat: 增加媒体格式校验，支持 JPEG、PNG、GIF、MP4、WebM、WebP 格式

sdk/src/main/kotlin/com/duooomi/ble/DuooomiBleSDK.kt

@@ -10,6 +10,7 @@ import kotlinx.coroutines.*
 import kotlinx.coroutines.flow.*
 import org.json.JSONObject
 import java.net.HttpURLConnection
+import java.net.URI
 import java.net.URL
 
 class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
@@ -303,6 +304,46 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
 
     // MARK: - High-Level APIs
 
+    companion object {
+        private val SUPPORTED_EXTENSIONS = setOf("jpeg", "jpg", "png", "gif", "mp4", "webm", "webp")
+        private val SUPPORTED_MIME_TYPES = setOf(
+            "image/jpeg", "image/png", "image/gif", "image/webp",
+            "video/mp4", "video/webm"
+        )
+    }
+
+    private fun extractExtension(urlString: String): String? {
+        return try {
+            val path = URI(urlString).path ?: return null
+            val dot = path.lastIndexOf('.')
+            if (dot >= 0 && dot < path.length - 1) path.substring(dot + 1).lowercase() else null
+        } catch (_: Exception) { null }
+    }
+
+    private suspend fun validateMediaFormat(url: String) {
+        val ext = extractExtension(url)
+        if (ext != null) {
+            if (SUPPORTED_EXTENSIONS.contains(ext)) return
+            throw DuooomiBleError.UnsupportedFormat(ext)
+        }
+
+        val mime = withContext(Dispatchers.IO) {
+            val conn = java.net.URL(url).openConnection() as HttpURLConnection
+            try {
+                conn.requestMethod = "HEAD"
+                conn.connectTimeout = 10_000
+                conn.readTimeout = 10_000
+                conn.contentType?.split(";")?.firstOrNull()?.trim()?.lowercase()
+            } finally {
+                conn.disconnect()
+            }
+        }
+
+        if (mime == null || !SUPPORTED_MIME_TYPES.contains(mime)) {
+            throw DuooomiBleError.UnsupportedFormat(mime ?: "unknown")
+        }
+    }
+
     suspend fun transferMedia(fileUrl: String) {
         ensureConnected()
         val url = fileUrl.trim()
@@ -315,6 +356,7 @@ class DuooomiBleSDK(context: Context, val config: DuooomiBleConfig) {
             aniUrl = url
             BleLog.i("Direct ANI transfer: $url", "Transfer")
         } else {
+            validateMediaFormat(url)
             BleLog.i("Converting to ANI: $url", "Transfer")
             try {
                 aniUrl = aniConverter.convert(url)