Skip creating .setup.jsdos bundles for Windows games

- Move platform detection before setup bundle creation
- Only create setup bundle when platform != 'windows'
- Also hide the Setup button in GameDetail for Windows games
- Windows setup executables (INSTALL.EXE) can't run in DOSBox anyway

frontend/src/pages/GameDetail.svelte

@@ -232,7 +232,7 @@
                 ▶ Unplayable
               </button>
             {/if}
-            {#if game.has_setup}
+            {#if game.has_setup && game.platform !== 'windows'}
               <button class="btn btn-setup" onclick={handleSetup}>🛠 Setup</button>
             {/if}
             <button class="btn" onclick={startEdit}>✏ Edit</button>

src/main/java/com/dostalgia/UploadResource.java

@@ -85,15 +85,16 @@ public class UploadResource {
             Path bundlePath = svc.getGamesDir().resolve(bundleFile);
             createBundle(extractDir, mainExe, bundlePath);
 
-            // Create setup bundle if a setup executable was found
-            if (setupExe != null) {
+            // Detect platform (DOS vs Windows) by reading the main EXE header
+            String platform = detectPlatform(Path.of(mainExe));
+
+            // Create setup bundle only if the game is a DOS executable
+            // (Windows setup bundles are useless — they need Windows to run)
+            if (setupExe != null && !"windows".equals(platform)) {
                 Path setupBundlePath = svc.getGamesDir().resolve(gameId + ".setup.jsdos");
                 createBundle(extractDir, setupExe, setupBundlePath);
             }
 
-            // Detect platform (DOS vs Windows) by reading the main EXE header
-            String platform = detectPlatform(Path.of(mainExe));
-
             // Save metadata
             Game game = new Game(gameId, title);
             game.setBundleFile(bundleFile);