fix: read beyond initial 0x80 buffer when PE/NE sig is at higher offset

PlatformDetector.detect() and GameService.detectPlatformInBundle()
both read only 0x80 bytes initially, but PE e_lfanew often points to
0x80 (128), putting the signature 2 bytes past the buffer. Added
fallback: re-read up to peOffset+2 bytes when needed.

Fixes PlatformDetectorTest detect_peHeader_returnsWindows and
detect_neHeader_returnsWindows assertions.

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

@@ -229,6 +229,17 @@ public class GameService implements GameStore {
                 if (entry.getName().equals(relExe.replace('\\', '/'))) {
                     byte[] buf = new byte[0x80];
                     int read = zis.readNBytes(buf, 0, buf.length);
+                    // Read more if PE/NE signature is beyond the initial buffer
+                    if (read >= 0x40) {
+                        int peOffset = (buf[0x3C] & 0xFF) | ((buf[0x3D] & 0xFF) << 8)
+                                     | ((buf[0x3E] & 0xFF) << 16) | ((buf[0x3F] & 0xFF) << 24);
+                        if (peOffset + 2 > read) {
+                            buf = java.util.Arrays.copyOf(buf, Math.max(buf.length, peOffset + 2));
+                            int remaining = buf.length - read;
+                            zis.readNBytes(buf, read, remaining);
+                            read = buf.length;
+                        }
+                    }
                     return PlatformDetector.detectFromBytes(buf, read);
                 }
                 zis.closeEntry();

src/main/java/com/dostalgia/PlatformDetector.java

@@ -31,6 +31,20 @@ public class PlatformDetector {
         try (var fis = Files.newInputStream(exePath)) {
             byte[] buf = new byte[0x80];
             int read = fis.readNBytes(buf, 0, buf.length);
+            // If the PE/NE signature is beyond the initial buffer, read more
+            if (read >= 0x40) {
+                int peOffset = (buf[0x3C] & 0xFF)
+                             | ((buf[0x3D] & 0xFF) << 8)
+                             | ((buf[0x3E] & 0xFF) << 16)
+                             | ((buf[0x3F] & 0xFF) << 24);
+                if (peOffset + 2 > read) {
+                    // Need to read beyond the initial buffer
+                    buf = java.util.Arrays.copyOf(buf, Math.max(buf.length, peOffset + 2));
+                    int remaining = buf.length - read;
+                    fis.readNBytes(buf, read, remaining);
+                    read = buf.length;
+                }
+            }
             return detectFromBytes(buf, read);
         } catch (IOException e) {
             LOG.warning("Could not read EXE header for " + exePath + ": " + e.getMessage());