fix: delete uses @HTTP hasBody + JsonObject return type

- Retrofit @DELETE doesn't support @Body — switched to @HTTP(method=DELETE, hasBody=true)
- Return type changed from Map<String,Any?> to JsonObject (kotlinx-serialization
  can't deserialize untyped maps)
- Fixed double-slash in download URL (baseUrl trailing slash)
- Cleaned up download progress tracking (emit outside withContext(IO))

android/app/src/main/java/com/yarisobd/app/DashcamViewModel.kt

@@ -144,7 +144,14 @@ class DashcamViewModel(application: Application) : AndroidViewModel(application)
     fun deleteVideo(video: VideoFile) {
         viewModelScope.launch {
             try {
-                api.deleteVideo(mapOf("path" to video.path))
+                val result = api.deleteVideo(mapOf("path" to video.path))
+                val status = result["status"]?.let { it.toString().trim('"') } ?: "unknown"
+                if (status == "ok") {
+                    _downloadEvents.emit("✓ Deleted: ${video.path}")
+                } else {
+                    val msg = result["message"]?.let { it.toString().trim('"') } ?: status
+                    _downloadEvents.emit("✗ Delete: $msg")
+                }
                 loadVideos()
             } catch (e: Exception) {
                 _error.value = "Delete failed: ${e.message}"

android/app/src/main/java/com/yarisobd/app/data/remote/PiApi.kt

@@ -2,6 +2,7 @@ package com.yarisobd.app.data.remote
 
 import com.yarisobd.app.data.remote.dto.GpsStatus
 import com.yarisobd.app.data.remote.dto.VideoListResponse
+import kotlinx.serialization.json.JsonObject
 import okhttp3.ResponseBody
 import retrofit2.http.Body
 import retrofit2.http.GET
@@ -33,5 +34,5 @@ interface PiApi {
 
     /** Delete local copy only */
     @HTTP(method = "DELETE", path = "/api/local-video", hasBody = true)
-    suspend fun deleteVideo(@Body body: Map<String, String>): Map<String, Any?>
+    suspend fun deleteVideo(@Body body: Map<String, String>): JsonObject
 }