fix: preserve CD image mounts when changing executable

GameService.buildDosboxConfBytes() was rebuilding dosbox.conf with
only the executable path — CD image mount lines were lost.

- Added findCdImagesInBundle() to scan a .jsdos ZIP for CD images
- buildDosboxConfBytes() now accepts List<String> cdImages and
  generates imgmount lines (same logic as UploadResource)
- Both setExecutable() and streamSetupBundle() now scan for
  and include CD images when regenerating config

src/main/java/com/dostalgia/GameService.java

@@ -166,8 +166,9 @@ public class GameService {
             throw new NoSuchFileException("Bundle not found: " + bundleFile);
         }
 
-        // Build new config entries
-        byte[] newDosboxConf = buildDosboxConfBytes(executable);
+        // Build new config entries — preserve any CD images in the bundle
+        List<String> cdImages = findCdImagesInBundle(bundlePath);
+        byte[] newDosboxConf = buildDosboxConfBytes(executable, cdImages);
         byte[] newJsdosJson = buildJsdosJsonBytes(executable);
 
         // Patch the ZIP: read old, write new with modified config entries
@@ -203,8 +204,28 @@ public class GameService {
         save(game);
     }
 
-    /** Build a dosbox.conf for a given executable path. */
-    private byte[] buildDosboxConfBytes(String relExe) {
+    /** Scan a .jsdos bundle for CD image files (preserves the case from the ZIP entry). */
+    private List<String> findCdImagesInBundle(Path bundlePath) throws IOException {
+        Set<String> cdExt = Set.of(".iso", ".cue", ".img", ".ccd", ".bin");
+        List<String> cds = new ArrayList<>();
+        try (var zis = new java.util.zip.ZipInputStream(Files.newInputStream(bundlePath))) {
+            java.util.zip.ZipEntry entry;
+            while ((entry = zis.getNextEntry()) != null) {
+                if (entry.isDirectory()) continue;
+                String name = entry.getName().toLowerCase();
+                int dot = name.lastIndexOf('.');
+                if (dot >= 0 && cdExt.contains(name.substring(dot))) {
+                    cds.add(entry.getName()); // preserve original filename casing
+                }
+                zis.closeEntry();
+            }
+        }
+        cds.sort(String::compareTo);
+        return cds;
+    }
+
+    /** Build a dosbox.conf for a given executable path and optional CD images. */
+    private byte[] buildDosboxConfBytes(String relExe, List<String> cdImages) {
         var parts = splitExePath(relExe);
         String dir = parts[0];
         String exe = parts[1];
@@ -214,7 +235,16 @@ public class GameService {
         sb.append("[mixer]\nnosound=false\nrate=44100\n\n");
         sb.append("[sblaster]\nsbtype=sb16\nirq=7\ndma=1\nhdma=5\n\n");
         sb.append("[dos]\nxms=true\nems=true\numb=true\n\n");
-        sb.append("[autoexec]\n@echo off\nmount c .\nc:\n");
+        sb.append("[autoexec]\n@echo off\nmount c .\n");
+        // Mount CD images as D:, E:, … so games can find their CD
+        char driveLetter = 'D';
+        for (String img : cdImages) {
+            String imgLower = img.toLowerCase();
+            String flags = imgLower.endsWith(".bin") ? " -t cdrom -fs iso" : " -t cdrom";
+            sb.append("imgmount ").append(driveLetter).append(" \"").append(img).append("\"").append(flags).append("\n");
+            driveLetter++;
+        }
+        sb.append("c:\n");
         if (dir != null) {
             sb.append("path=c:\\\n");
             sb.append("cd ").append(dir).append("\n");
@@ -299,7 +329,9 @@ public class GameService {
             throw new NoSuchFileException("Bundle not found: " + game.getBundleFile());
         }
 
-        byte[] newDosboxConf = buildDosboxConfBytes(setupExe);
+        // Build new config entries — preserve any CD images in the bundle
+        List<String> cdImages = findCdImagesInBundle(bundlePath);
+        byte[] newDosboxConf = buildDosboxConfBytes(setupExe, cdImages);
         byte[] newJsdosJson = buildJsdosJsonBytes(setupExe);
 
         try (var zis = new java.util.zip.ZipInputStream(Files.newInputStream(bundlePath));