feat: media_async + media_index modules, media_files table, tests

- media_async: thread-per-task async engine with primitives (sha256, sign, copy, uuid, file_size)
- media_index: media_files DB table with register_async for indexing chunks
- chat_msg: async media submission via register_async, simplified chat_msg_submit fields
- voice_recorder/attachment_sender: write single file (no chunk splitting on caller side)
- inputbar/messagelist: updated to new simplified submit interface
- test_media_async: 4-thread stress test (200K ops / 2 sec, 0 errors)
- test_media_index: 9 cases covering commit edge cases + async flow
- build: Makefile.am, CMakeLists.txt, utun_sources.cmake updated

tools/chatgui-android/app/src/main/java/com/utun/chat/data/ChatRepository.kt

@@ -9,7 +9,7 @@ data class Channel(val id: String, val name: String, val lastMsgAt: Long = 0, va
 data class Message(val id: Long, val author: String, val text: String, val ts: Long,
                    val isOutgoing: Boolean = false, val contentType: String = "text/plain",
                    val filePath: String = "", val waveform: List<Float> = emptyList(),
-                   val voiceDurationMs: Int = 0)
+                   val voiceDurationMs: Int = 0, val fileSize: Long = 0)
 
 class ChatRepository {
     private val myNodeId: Long = NativeLib.getMyNodeId()
@@ -53,6 +53,9 @@ class ChatRepository {
                 val contentType = obj.optString("contentType", "text/plain")
                 val filePath = obj.optString("filePath", "")
 
+                var displayText = text
+                var fileSize = 0L
+
                 /* Parse base64 waveform from voice message text (format: "wf=<100 chars A-Za-z0-9+/>;dur=1234;") */
                 var waveform = emptyList<Float>()
                 var voiceDurationMs = 0
@@ -88,16 +91,30 @@ class ChatRepository {
                     } catch (_: Exception) {}
                 }
 
+                /* Parse file attachment: "filename.ext|file_size|block_size|num_blocks|sigs" */
+                if (contentType == "application/octet-stream") {
+                    try {
+                        val pipeIdx = text.indexOf('|')
+                        if (pipeIdx > 0) {
+                            displayText = text.substring(0, pipeIdx)
+                            val metaParts = text.substring(pipeIdx + 1).split("|")
+                            if (metaParts.isNotEmpty())
+                                fileSize = metaParts[0].toLongOrNull() ?: 0L
+                        }
+                    } catch (_: Exception) {}
+                }
+
                 list.add(Message(
                     id = obj.getLong("id"),
                     author = obj.getString("author"),
-                    text = text,
+                    text = displayText,
                     ts = obj.getLong("ts"),
                     isOutgoing = obj.optBoolean("isOutgoing", false),
                     contentType = contentType,
                     filePath = filePath,
                     waveform = waveform,
-                    voiceDurationMs = voiceDurationMs
+                    voiceDurationMs = voiceDurationMs,
+                    fileSize = fileSize
                 ))
             }
         } catch (e: Exception) { Log.w("utun-gui", "getMessages error", e) }

tools/chatgui-android/app/src/main/java/com/utun/chat/data/ConfigProvider.kt

@@ -36,6 +36,9 @@ class ConfigProvider(private val context: Context) {
     private val logUdpIp = stringPreferencesKey("log_udp_ip")
     private val logUdpPort = intPreferencesKey("log_udp_port")
     private val serversJson = stringPreferencesKey("servers")
+    private val storageAutoload = intPreferencesKey("storage_autoload")
+    private val storageAutoloadMaxsizeMb = intPreferencesKey("storage_autoload_maxsize_mb")
+    private val storageMaxsizeGb = intPreferencesKey("storage_maxsize_gb")
     private val firstLaunchDone = booleanPreferencesKey("first_launch_done")
 
     private val gson = Gson()
@@ -130,6 +133,9 @@ class ConfigProvider(private val context: Context) {
             key == "node.listen_port" -> context.dataStore.data.first()[nodeListenPort] ?: 12345
             key == "control.port" -> context.dataStore.data.first()[controlPort] ?: 9999
             key == "log_udp.port" -> context.dataStore.data.first()[logUdpPort] ?: 9999
+            key == "storage_autoload" -> context.dataStore.data.first()[storageAutoload] ?: 1
+            key == "storage_autoload_maxsize_mb" -> context.dataStore.data.first()[storageAutoloadMaxsizeMb] ?: 10
+            key == "storage_maxsize_gb" -> context.dataStore.data.first()[storageMaxsizeGb] ?: 1
             else -> 0
         }
     }
@@ -149,6 +155,9 @@ class ConfigProvider(private val context: Context) {
                 "debug.categories" -> prefs[debugCategories] = value
                 "log_udp.ip" -> prefs[logUdpIp] = value
                 "log_udp.port" -> prefs[logUdpPort] = value.toIntOrNull() ?: 0
+                "storage_autoload" -> prefs[storageAutoload] = value.toIntOrNull() ?: 1
+                "storage_autoload_maxsize_mb" -> prefs[storageAutoloadMaxsizeMb] = value.toIntOrNull() ?: 10
+                "storage_maxsize_gb" -> prefs[storageMaxsizeGb] = value.toIntOrNull() ?: 1
             }
         }
     }

tools/chatgui-android/app/src/main/java/com/utun/chat/ui/components/MessageBubble.kt

@@ -62,7 +62,7 @@ fun MessageBubble(message: Message, playbackState: ChatViewModel.PlaybackState =
 
             when {
                 isVoice -> VoiceBubble(message, textColor, isActive, playbackState, onPlayVoice, onSeekVoice)
-                isMedia -> Text("\uD83D\uDCC4 ${message.text}", fontSize = 15.sp, color = textColor)
+                isMedia -> FileBubble(message, textColor)
                 else -> {
                     Text(message.author, fontSize = 13.sp, fontWeight = FontWeight.Bold, color = textColor.copy(alpha = 0.7f))
                     Spacer(Modifier.height(2.dp))
@@ -167,6 +167,26 @@ private fun VoiceBubble(message: Message, textColor: Color, isActive: Boolean,
     }
 }
 
+@Composable
+private fun FileBubble(message: Message, textColor: Color) {
+    Column {
+        Text(message.text, fontSize = 15.sp, color = textColor, fontWeight = FontWeight.Bold)
+        Spacer(Modifier.height(2.dp))
+        Text(formatFileSize(message.fileSize), fontSize = 12.sp, color = textColor.copy(alpha = 0.5f))
+    }
+}
+
+private fun formatFileSize(bytes: Long): String {
+    if (bytes <= 0) return ""
+    if (bytes < 1024) return "${bytes}B"
+    val kb = bytes / 1024.0
+    if (kb < 1024.0) return if (kb < 10.0) "%.1fKB".format(kb) else "%.0fKB".format(kb)
+    val mb = kb / 1024.0
+    if (mb < 1024.0) return if (mb < 10.0) "%.1fMB".format(mb) else "%.0fMB".format(mb)
+    val gb = mb / 1024.0
+    return "%.1fGB".format(gb)
+}
+
 private fun formatDurationMs(ms: Int): String {
     val secs = ms / 1000
     return "%d:%02d".format(secs / 60, secs % 60)

tools/chatgui-android/app/src/main/java/com/utun/chat/ui/screens/SettingsScreen.kt

@@ -42,7 +42,7 @@ fun SettingsScreen(vm: ChatViewModel, onBack: () -> Unit, onExit: () -> Unit = {
     var dirty by remember { mutableStateOf(false) }
 
     var tabIndex by remember { mutableStateOf(0) }
-    val tabs = listOf("Settings", "Audio")
+    val tabs = listOf("Settings", "Audio", "Storage")
 
     val handleBack = {
         if (dirty) {
@@ -73,6 +73,7 @@ fun SettingsScreen(vm: ChatViewModel, onBack: () -> Unit, onExit: () -> Unit = {
             when (tabIndex) {
                 0 -> GeneralSettingsTab(vm, dirty, onDirty = { dirty = it }, onExit)
                 1 -> AudioSettingsTab(vm)
+                2 -> StorageSettingsTab()
             }
         }
     }
@@ -414,6 +415,52 @@ private fun AudioSettingsTab(vm: ChatViewModel) {
     }
 }
 
+/* ── Storage Settings Tab ── */
+
+@Composable
+private fun StorageSettingsTab() {
+    val provider = ChatApplication.instance.configProvider
+    val scope = rememberCoroutineScope()
+
+    var autoload by remember { mutableStateOf(true) }
+    var autoloadMaxSizeMb by remember { mutableStateOf("10") }
+    var maxStorageGb by remember { mutableStateOf("1") }
+
+    LaunchedEffect(Unit) {
+        autoload = provider.getInt("storage_autoload") != 0
+        autoloadMaxSizeMb = provider.getInt("storage_autoload_maxsize_mb").toString()
+        maxStorageGb = provider.getInt("storage_maxsize_gb").toString()
+    }
+
+    Column(
+        modifier = Modifier.padding(16.dp).verticalScroll(rememberScrollState()),
+        verticalArrangement = Arrangement.spacedBy(12.dp)
+    ) {
+        Text("Media Storage", style = MaterialTheme.typography.titleMedium)
+        Row(verticalAlignment = Alignment.CenterVertically) {
+            Text("Autoload media", modifier = Modifier.weight(1f))
+            Switch(checked = autoload, onCheckedChange = {
+                autoload = it
+                scope.launch { provider.setValue("storage_autoload", if (it) "1" else "0") }
+            })
+        }
+
+        HorizontalDivider(Modifier.padding(vertical = 4.dp))
+
+        OutlinedTextField(autoloadMaxSizeMb,
+            { v -> autoloadMaxSizeMb = v; val nb = v.toIntOrNull(); if (nb != null && nb in 1..500) scope.launch { provider.setValue("storage_autoload_maxsize_mb", v) } },
+            label = { Text("Autoload max size (MB)") },
+            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
+            singleLine = true, modifier = Modifier.padding(top = 4.dp))
+
+        OutlinedTextField(maxStorageGb,
+            { v -> maxStorageGb = v; val nb = v.toIntOrNull(); if (nb != null && nb in 1..100) scope.launch { provider.setValue("storage_maxsize_gb", v) } },
+            label = { Text("Max storage size (GB)") },
+            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
+            singleLine = true)
+    }
+}
+
 /* ── Labeled Slider ── */
 
 @Composable