Prefer larger files over shallow depth in findMainExe

Size is a better indicator of 'this is the actual game' than depth.
A 1MB+ FALLOUT.EXE in a subdirectory should beat a 50KB BOOTME.EXE
at the root. Sort order: non-installer → DOS → size → depth.

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

@@ -261,7 +261,7 @@ public class UploadResource {
 
         if (candidates.isEmpty()) return null;
 
-        // Prefer: non-installer → DOS platform → shallow depth → larger file
+        // Prefer: non-installer → DOS platform → larger file → shallow depth
         candidates.sort(Comparator
             .comparingInt((Candidate c) -> c.isInstaller() ? 1 : 0)
             .thenComparingInt(c -> {
@@ -270,8 +270,8 @@ public class UploadResource {
                 if (c.platform() == null) return 1;
                 return 2; // "windows"
             })
-            .thenComparingInt(Candidate::depth)
-            .thenComparingLong(c -> -c.size()));
+            .thenComparingLong(c -> -c.size())
+            .thenComparingInt(Candidate::depth));
 
         return candidates.getFirst().path();
     }