fix: reliable first-message send, QR routing, auto-lock recovery

Fixes reported by testers and found in an app review:

- First message right after install no longer fails. Before the app
  finished registering with the relay, the outgoing message could crash on
  a null delivery address. The profile field is now optional and the send
  path throws a clear "still connecting, try again shortly" error while
  registration completes in the background.
- The QR code and share link now appear only once the delivery address is
  ready. Previously a link generated before the first connection lacked
  routing, so the other side could not send the first message. The screen
  now shows a connecting state and reactively swaps in the QR when ready.
- Incomplete contact links are rejected on import instead of failing at
  first send, with a clear prompt to ask for a fresh link.
- Auto-lock no longer silences the app: after locking and unlocking,
  messaging is restarted (it previously stayed dead until app restart).
- Group messages are marked failed on a non-per-member send error instead
  of hanging in the "sending" state forever.
- Hardened the relay client against a rare duplicate connection when
  toggling Tor or locking mid-connect, and fromShareString now rejects a
  delivery address of the wrong length.
- Pin unifiedpush below 6.2.0 to drop the webcrypto dependency (its native
  framework lacks LC_ENCRYPTION_INFO and blocked the iOS upload).
- Skip Android release lint (network dependency check hangs on the build
  host and adds no value for a Flutter app).

app/linux/flutter/generated_plugin_registrant.cc

@@ -10,9 +10,7 @@
 #include <file_selector_linux/file_selector_plugin.h>
 #include <flutter_secure_storage_linux/flutter_secure_storage_linux_plugin.h>
 #include <record_linux/record_linux_plugin.h>
-#include <screen_retriever_linux/screen_retriever_linux_plugin.h>
 #include <url_launcher_linux/url_launcher_plugin.h>
-#include <window_manager/window_manager_plugin.h>
 
 void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) audioplayers_linux_registrar =
@@ -27,13 +25,7 @@ void fl_register_plugins(FlPluginRegistry* registry) {
   g_autoptr(FlPluginRegistrar) record_linux_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "RecordLinuxPlugin");
   record_linux_plugin_register_with_registrar(record_linux_registrar);
-  g_autoptr(FlPluginRegistrar) screen_retriever_linux_registrar =
-      fl_plugin_registry_get_registrar_for_plugin(registry, "ScreenRetrieverLinuxPlugin");
-  screen_retriever_linux_plugin_register_with_registrar(screen_retriever_linux_registrar);
   g_autoptr(FlPluginRegistrar) url_launcher_linux_registrar =
       fl_plugin_registry_get_registrar_for_plugin(registry, "UrlLauncherPlugin");
   url_launcher_plugin_register_with_registrar(url_launcher_linux_registrar);
-  g_autoptr(FlPluginRegistrar) window_manager_registrar =
-      fl_plugin_registry_get_registrar_for_plugin(registry, "WindowManagerPlugin");
-  window_manager_plugin_register_with_registrar(window_manager_registrar);
 }

app/linux/flutter/generated_plugins.cmake

@@ -7,9 +7,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
   file_selector_linux
   flutter_secure_storage_linux
   record_linux
-  screen_retriever_linux
   url_launcher_linux
-  window_manager
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST