Fix: prioritize non-installer executables over depth in findMainExe

The sort was: depth → non-installer → size.
This meant a root-level SETUP.EXE (depth 1, installer) beat a
subdirectory FALLOUT.EXE (depth 2, non-installer).

New sort: non-installer → depth → size.
Now any non-installer game EXE wins over installers regardless of depth.

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

@@ -261,8 +261,8 @@ public class UploadResource {
         if (candidates.isEmpty()) return null;
 
         candidates.sort(Comparator
-            .comparingInt(Candidate::depth)
-            .thenComparingInt(c -> c.isInstaller() ? 1 : 0)
+            .comparingInt(c -> c.isInstaller() ? 1 : 0) // non-installer first
+            .thenComparingInt(Candidate::depth)
             .thenComparingLong(c -> -c.size())); // larger files first
 
         return candidates.getFirst().path();