restore dedup: mount one CD image per directory, prefer .bin over .cue

Since GameService now preserves CD images when regenerating configs,
the dedup logic is safe to re-add. Deduplicates by parent directory
so a .bin and .cue from the same folder only produce one imgmount.
Alphabetical sort ensures .bin (b) is mounted before .cue (c).

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

@@ -236,9 +236,14 @@ public class GameService {
         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 .\n");
-        // Mount CD images as D:, E:, … so games can find their CD
+        // Mount CD images as D:, E:, … so games can find their CD.
+        // Deduplicate by parent directory — prefer .bin over .cue.
+        Set<String> seenDirs = new java.util.HashSet<>();
         char driveLetter = 'D';
         for (String img : cdImages) {
+            int slashIdx = img.lastIndexOf('/');
+            String parentDir = slashIdx >= 0 ? img.substring(0, slashIdx) : "";
+            if (!seenDirs.add(parentDir)) continue;
             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");

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

@@ -584,9 +584,16 @@ public class UploadResource {
         sb.append("[autoexec]\n");
         sb.append("@echo off\n");
         sb.append("mount c .\n");
-        // Mount CD images as D:, E:, … so games can find their CD
+        // Mount CD images as D:, E:, … so games can find their CD.
+        // Deduplicate by parent directory — prefer .bin over .cue since
+        // .bin files sort first alphabetically and avoid .cue FILE path
+        // case-mismatch issues.
+        Set<String> seenDirs = new java.util.HashSet<>();
         char driveLetter = 'D';
         for (String img : cdImages) {
+            int slashIdx = img.lastIndexOf('/');
+            String parentDir = slashIdx >= 0 ? img.substring(0, slashIdx) : "";
+            if (!seenDirs.add(parentDir)) continue; // already mounted from this dir
             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");