Auto-exclude disk image files (.img .iso .ccd .sub etc.) from .jsdos bundles

Many DOS game ZIPs include CloneCD backups (.ccd/.img/.sub) or
other disk images that are not needed for gameplay — the game data
is already extracted in the working directory. These can be 300MB+
and cause WASM memory exhaustion in js-dos.

Added a SKIP_EXT set that filters out known disk image extensions
during game file pass. The .jsdos config pass is unaffected.

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

@@ -279,6 +279,13 @@ public class UploadResource {
 
     // ─── Bundle Creation ─────────────────────────────────────────
 
+    /** File extensions that are never game data and should be excluded from .jsdos bundles. */
+    private static final java.util.Set<String> SKIP_EXT = java.util.Set.of(
+        ".img", ".iso", ".nrg", ".mdf", ".mds",  // disk images
+        ".ccd", ".sub", ".cue",                   // CloneCD / CUE sheets
+        ".dmg"                                     // Mac disk images
+    );
+
     private void createBundle(Path extractDir, String exePath, Path bundlePath) throws IOException {
         // Write .jsdos config directly into the extract directory
         Path jsdos = extractDir.resolve(".jsdos");
@@ -333,6 +340,11 @@ public class UploadResource {
             try (var walk = Files.walk(extractDir)) {
                 walk.filter(Files::isRegularFile)
                     .filter(f -> !f.startsWith(jsdos))
+                    .filter(f -> {
+                        String n = f.getFileName().toString().toLowerCase();
+                        int dot = n.lastIndexOf('.');
+                        return dot < 0 || !SKIP_EXT.contains(n.substring(dot));
+                    })
                     .sorted() // deterministic order
                     .forEach(writeFile);
             }