Skip self-extracting archive executables (PKSFX etc.)

- Added archiver/compression tool names to SKIP_EXE_NAMES (pksfx,
  pkzip, pkunzip, unzip, arj, rar, lha, etc.)
- Added isLikelySelfExtractor() which reads the EXE body looking for
  PKWARE signatures (PKZIP/PKSFX strings and PK\x03\x04 local file
  headers) — catches renamed self-extractors regardless of filename
- Both filters applied during findMainExe candidate collection

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

@@ -255,6 +255,10 @@ public class UploadResource {
                 if (SKIP_EXE_NAMES.contains(stem))
                     return FileVisitResult.CONTINUE;
 
+                // Skip self-extracting archive executables (PKSFX, PKZIP stubs, etc.)
+                if (isLikelySelfExtractor(f))
+                    return FileVisitResult.CONTINUE;
+
                 boolean installer = name.contains("install") || name.contains("setup") || name.contains("config");
                 int depth = f.getNameCount() - dir.getNameCount();
                 String platform = detectPlatform(f);
@@ -280,6 +284,38 @@ public class UploadResource {
         return candidates.getFirst().path();
     }
 
+    /**
+     * Check if an executable is likely a self-extracting archive (PKSFX, PKZIP stub, etc.)
+     * by looking for characteristic PKWARE signatures in the MS-DOS stub portion.
+     * Self-extractors contain embedded archive data and are not game executables.
+     */
+    static boolean isLikelySelfExtractor(Path exePath) {
+        try (var fis = Files.newInputStream(exePath)) {
+            byte[] buf = new byte[4096];
+            int read = fis.readNBytes(buf, 0, buf.length);
+            if (read < 0x40) return false;
+            // Must start with MZ
+            if (buf[0] != 0x4D || buf[1] != 0x5A) return false;
+            // Scan the MS-DOS stub area (after the header) for PKWARE signatures
+            // PKSFX/PKZIP stubs contain strings like "PKZIP", "PK", "PKSFX"
+            // in the first few KB of the executable
+            String content = new String(buf, 0, read, java.nio.charset.StandardCharsets.ISO_8859_1);
+            if (content.contains("PKZIP") || content.contains("PKSFX"))
+                return true;
+            // Check for the typical PKWARE "PK\x03\x04" local file header signature
+            // which appears in append-to-exe style self-extractors
+            for (int i = 0; i < read - 4; i++) {
+                if (buf[i] == 0x50 && buf[i+1] == 0x4B && buf[i+2] == 0x03 && buf[i+3] == 0x04)
+                    return true;
+                if (buf[i] == 0x50 && buf[i+1] == 0x4B && buf[i+2] == 0x05 && buf[i+3] == 0x06)
+                    return true;
+            }
+            return false;
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
     // ─── Setup Executable Detection ─────────────────────────────
 
     /**
@@ -341,7 +377,15 @@ public class UploadResource {
         "emm386",                                  // Expanded memory manager
         "himem", "himemx",                         // Extended memory managers
         "debug",                                   // Debugger
-        "uninst", "uninstall", "uninstaller"        // Uninstallers
+        "uninst", "uninstall", "uninstaller",       // Uninstallers
+        // Compression / archive tools (self-extractors)
+        "pksfx", "pkzip", "pkunzip",               // PKWARE
+        "unzip", "zip", "zip2exe",                 // Info-ZIP
+        "arj", "arj32",                            // ARJ
+        "lha", "lha32", "lzh",                     // LHA/LHarc
+        "rar", "unrar",                            // RAR
+        "ace", "unace",                            // ACE
+        "zoo", "arc", "ha", "cab"                  // others
     );
 
     private void createBundle(Path extractDir, String exePath, Path bundlePath) throws IOException {