Fix: Add @ConscryptMode annotation to FileTransferTest to resolve UnsatisfiedLinkError (#543)

Robolectric 4.9+ uses Conscrypt as the default security provider, which
requires native libraries that aren't available in the test environment.
Adding @ConscryptMode(Mode.OFF) disables Conscrypt and uses BouncyCastle
instead, which resolves the test failures.

This fixes the build failures in FileTransferTest where all 9 tests were
failing with UnsatisfiedLinkError when Conscrypt tried to load native
libraries.

Fixes #542

app/src/test/kotlin/com/bitchat/FileTransferTest.kt

@@ -8,12 +8,14 @@ import org.junit.Assert.assertNotNull
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.ConscryptMode
 import java.io.File
 import java.nio.ByteBuffer
 import java.nio.ByteOrder
 import java.util.Date
 
 @RunWith(RobolectricTestRunner::class)
+@ConscryptMode(ConscryptMode.Mode.OFF) // Disable Conscrypt to avoid native library loading issues
 class FileTransferTest {
 
     @Test