dm: прямой обмен сообщениями (DM) + soundtouch + архитектура звонков

- src/dm/: dm_core/dm_crypto/dm_mailbox — прямой обмен сообщениями (DM)
- lib/soundtouch-master/: vendored SoundTouch (изменение темпа/высоты аудио)
- doc/dm_arch.md, doc/chat_call_arch.md: архитектура DM и звонков
- tests: test_dm.c, test_dm_e2e.c
- chat: рефакторинг chat_* модулей, member_sync, invite_build
- chatgui/chatgui-android: синхронизация с новым API чата
- lib/u_async, debug_config, utun_instance: сопутствующие изменения

src/utun_instance.c

@@ -18,6 +18,8 @@
 #include "chat/chat_core.h"
 #include "chat/chat_sync.h"
 #include "chat/chat_headless_control.h"
+#include "dm/dm_core.h"
+#include "dm/dm_mailbox.h"
 #include "broadcast.h"
 #include "stcp_server.h"
 #include "control_server.h"
@@ -478,8 +480,10 @@ void utun_instance_destroy(struct UTUN_INSTANCE *instance) {
     DEBUG_INFO(DEBUG_CATEGORY_SYS, "[DESTROY] G done — ETCP sockets");
 
     /* Phase H: chat */
-    chat_headless_control_destroy();
+    chat_headless_control_destroy(instance);
     chat_media_startup_backfill_destroy(instance);
+    dm_mailbox_destroy(instance);
+    dm_core_destroy(instance);
     chat_sync_destroy(instance);
     chat_core_destroy(instance);
     DEBUG_INFO(DEBUG_CATEGORY_SYS, "[DESTROY] H done — chat");
@@ -672,8 +676,11 @@ int utun_instance_init(struct UTUN_INSTANCE *instance) {
         snprintf(db_file, sizeof(db_file), "%s/chats.db", instance->config->global.db_path);
         if (chat_core_init(instance, db_file) == 0) {
             chat_sync_init(instance);
-            chat_media_backfill();
+            chat_media_backfill(instance);
             chat_media_startup_backfill_init(instance);
+            /* dm_mailbox до dm_core: dm_core_init ставит deliver-cb в mailbox */
+            dm_mailbox_init(instance);
+            dm_core_init(instance);
         }
     }