ci(desktop): retry vlcDownload on transient network failures

Every desktop packaging job (Windows MSI, macOS DMG, Linux DEB) currently
breaks on the smallest blip when fetching VLC from get.videolan.org. The
`ir.mahozad.vlc-setup` plugin registers `vlcDownload` / `upxDownload`
tasks that extend `de.undercouch.gradle.tasks.download.Download`, but it
does not configure retries or a generous read timeout, so a single
`SocketTimeoutException` aborts the build.

Recent main runs all failed at the same step:

    > Task :desktopApp:vlcDownload FAILED
    > A failure occurred while executing ...DefaultWorkAction
       > java.net.SocketTimeoutException: Read timed out

Configure all `Download` tasks in this project with:

  - 5 attempts total (initial + 4 retries),
  - 30 s connect timeout,
  - 5 min read timeout (VLC archives are 40-90 MB and the mirror can be
    slow under load),
  - `tempAndMove` so a partial download from one attempt cannot poison
    the next.

This is a CI-only change \u2014 it does not alter what gets bundled, just
makes the fetch resilient.

desktopApp/build.gradle.kts

@@ -1,3 +1,4 @@
+import de.undercouch.gradle.tasks.download.Download
 import org.jetbrains.compose.desktop.application.dsl.TargetFormat
 import java.nio.file.Files
 
@@ -144,6 +145,25 @@ tasks.named("spotlessKotlin") {
     mustRunAfter("vlcSetup")
 }
 
+// `ir.mahozad.vlc-setup` registers `vlcDownload` / `upxDownload` tasks that
+// extend `de.undercouch.gradle.tasks.download.Download`. Defaults are 0 retries
+// and a short read timeout, so a transient blip on get.videolan.org fails the
+// whole desktop build on CI (Windows MSI, macOS DMG, Linux DEB). Configure all
+// Download tasks in this project to retry with generous timeouts so flaky
+// network conditions do not break packaging jobs.
+tasks.withType<Download>().configureEach {
+    // 5 attempts total (initial + 4 retries) before failing the task.
+    retries(4)
+    // 30s to establish a TCP / TLS connection.
+    connectTimeout(30_000)
+    // 5 minutes per attempt for the body — VLC archives are 40-90 MB and
+    // get.videolan.org can be slow under load.
+    readTimeout(5 * 60_000)
+    // Stage to a temp file and rename only on full success, so a partial
+    // download from one attempt cannot poison the next.
+    tempAndMove(true)
+}
+
 // --- AppImage packaging (Linux) ---
 //
 // Compose Multiplatform's TargetFormat.AppImage is known-broken in 1.10.x (CMP-7101).