multiplatform: remove unused clipboard state polling that froze desktop UI

The desktop app polled full clipboard contents every second on the AWT
event thread to update ChatModel.clipboardHasText. On X11, each read
blocks up to sun.awt.datatransfer.timeout (10s) when the selection owner
does not respond (e.g. after KeePassXC's clipboard auto-clear), making
every click/scroll wait ~9s. clipboardHasText has had no readers since
its only consumer was removed in #4398, so the whole mechanism (desktop
poll, Android clip listener, onResume refresh, expect/actual, state
field) is deleted. See plans/2026-07-11-fix-desktop-clipboard-freeze.md.

apps/multiplatform/android/src/main/java/chat/simplex/app/MainActivity.kt

@@ -1,6 +1,5 @@
 package chat.simplex.app
 
-import android.content.Context
 import android.content.Intent
 import android.net.Uri
 import android.os.*
@@ -8,7 +7,6 @@ import android.view.View
 import android.view.WindowManager
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.compose.ui.platform.ClipboardManager
 import androidx.fragment.app.FragmentActivity
 import chat.simplex.app.model.NtfManager
 import chat.simplex.app.model.NtfManager.getUserIdFromIntent
@@ -21,7 +19,6 @@ import chat.simplex.common.views.helpers.*
 import chat.simplex.common.views.onboarding.*
 import chat.simplex.common.platform.*
 import chat.simplex.res.MR
-import kotlinx.coroutines.*
 import java.lang.ref.WeakReference
 
 class MainActivity: FragmentActivity() {
@@ -73,17 +70,6 @@ class MainActivity: FragmentActivity() {
   override fun onResume() {
     super.onResume()
     AppLock.recheckAuthState()
-    withApi {
-      delay(1000)
-      if (!isAppOnForeground) return@withApi
-      /**
-       * When the app calls [ClipboardManager.shareText] and a user copies text in clipboard, Android denies
-       * access to clipboard because the app considered in background.
-       * This will ensure that the app will get the event on resume
-       * */
-      val service = getSystemService(Context.CLIPBOARD_SERVICE) as android.content.ClipboardManager
-      chatModel.clipboardHasText.value = service.hasPrimaryClip()
-    }
   }
 
   override fun onPause() {