fix: wire PlatformDetector in ExecutableDetectorTest

ExecutableDetector uses @Inject for PlatformDetector, but tests
instantiate it directly via 'new' — CDI doesn't run. Manually set
the package-private 'platform' field in an instance initializer.

src/test/java/com/dostalgia/ExecutableDetectorTest.java

@@ -14,8 +14,14 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class ExecutableDetectorTest {
 
+    private final PlatformDetector platform = new PlatformDetector();
     private final ExecutableDetector detector = new ExecutableDetector();
 
+    // Manually wire dependencies since we're not in a CDI container
+    {
+        detector.platform = platform;
+    }
+
     @Test
     void findAll_findsExeComBat(@TempDir Path dir) throws Exception {
         Files.writeString(dir.resolve("GAME.EXE"), "MZ");