feat: block re-upload of files already on server + visible upload progress

- Hide upload button when file is in uploadedNames (already on server)
- UploadWorker still guards via /status already_uploaded check
- Indeterminate progress bar during Hashing/Checking phases
- Upload label always shows percentage

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

@@ -120,12 +120,21 @@ fun DownloadsScreen(
                             }
                             if (!dl.done) {
                                 Spacer(Modifier.height(8.dp))
+                                if (dl.progress > 0) {
                                     LinearProgressIndicator(
                                         progress = { dl.progress / 100f },
                                         modifier = Modifier.fillMaxWidth().height(6.dp).clip(RoundedCornerShape(3.dp)),
                                         color = MaterialTheme.colorScheme.tertiary,
                                         trackColor = MaterialTheme.colorScheme.surfaceVariant,
                                     )
+                                } else {
+                                    // Indeterminate bar so hashing/checking phases show visible activity
+                                    LinearProgressIndicator(
+                                        modifier = Modifier.fillMaxWidth().height(6.dp).clip(RoundedCornerShape(3.dp)),
+                                        color = MaterialTheme.colorScheme.tertiary,
+                                        trackColor = MaterialTheme.colorScheme.surfaceVariant,
+                                    )
+                                }
                             }
                         }
                     }
@@ -228,7 +237,7 @@ fun DownloadsScreen(
                             if (isDeleting) {
                                 CircularProgressIndicator(modifier = Modifier.size(20.dp), strokeWidth = 2.dp, color = MaterialTheme.colorScheme.error)
                             } else {
-                                if (credentialsConfigured) {
+                                if (credentialsConfigured && file.name !in uploadedNames) {
                                     IconButton(onClick = { onUpload(file) }) {
                                         Icon(Icons.Filled.CloudUpload, "Upload", tint = MaterialTheme.colorScheme.tertiary)
                                     }
@@ -248,7 +257,7 @@ fun DownloadsScreen(
 private fun uploadLabel(dl: ActiveDownload): String {
     val pct = "${dl.progress}%"
     val status = dl.status ?: return pct
-    return if (dl.progress > 0) "$status · $pct" else status
+    return "$status · $pct"
 }
 
 private fun formatSize(bytes: Long): String = when {