desktop: add WebP ImageIO plugin (TwelveMonkeys) so the image picker can decode WebP

apps/multiplatform/common/build.gradle.kts

@@ -151,6 +151,10 @@ kotlin {
         implementation("com.github.NanoHttpd.nanohttpd:nanohttpd:efb2ebf")
         implementation("com.github.NanoHttpd.nanohttpd:nanohttpd-websocket:efb2ebf")
         implementation("com.squareup.okhttp3:okhttp:4.12.0")
+        // WebP decoder for ImageIO — desktop's javax.imageio.ImageIO ships only JPEG/PNG/GIF/BMP
+        // by default. Without this, picking a WebP via the image picker falls into the catch-block
+        // at Utils.desktop.kt:getBitmapFromUri and shows "image cannot be decoded".
+        implementation("com.twelvemonkeys.imageio:imageio-webp:3.11.0")
       }
     }
     val desktopTest by getting

apps/multiplatform/common/src/commonTest/kotlin/chat/simplex/app/MetadataStripTest.kt

@@ -937,6 +937,17 @@ class CorruptionCheckTest {
     assertTrue(image.width > 0 && image.height > 0)
   }
 
+  @Test fun testStrippedWebpDecodable() {
+    // Verifies that (a) the WebP stripper produces a valid file and (b) the TwelveMonkeys
+    // imageio-webp plugin is registered on desktop so `ImageIO.read` doesn't return null —
+    // without the plugin the desktop image picker rejects every WebP with "cannot be decoded".
+    val input = loadResource("webp_with_exif.webp")
+    val output = stripWebPMetadata(input)
+    val image = javax.imageio.ImageIO.read(java.io.ByteArrayInputStream(output))
+    assertNotNull(image, "Stripped WebP should be decodable via ImageIO")
+    assertTrue(image.width > 0 && image.height > 0)
+  }
+
   @Test fun testStrippedMp4HasValidStructure() {
     val inputFile = File.createTempFile("test_", ".mp4")
     inputFile.writeBytes(loadResource("mp4_with_gps.mp4"))