feat: replace Minecraft logo with LCRE logo at 80% scale

Replace MenuTitle and MenuTitleSmall bitmaps in skinHDWin.swf and
skinWin.swf with the custom LCRE (Legacy Console Edition Revelations)
logo, scaled to 80% within the original bitmap canvas to avoid
occlusion by the load/join menu.

Add ReplaceLogo.java and ExtractFromArc.java tools for SWF bitmap
replacement and arc file extraction. Keep original arc as .bak.

tools/ExtractFromArc.java

@@ -0,0 +1,42 @@
+import java.io.*;
+import java.nio.file.*;
+
+public class ExtractFromArc {
+    public static void main(String[] args) throws Exception {
+        if (args.length < 3) {
+            System.out.println("Usage: ExtractFromArc <arc_file> <filename> <output_path>");
+            System.exit(1);
+        }
+        String arcPath = args[0];
+        String target = args[1];
+        String outPath = args[2];
+
+        DataInputStream dis = new DataInputStream(new FileInputStream(arcPath));
+        int numFiles = dis.readInt();
+        int foundOffset = -1, foundSize = -1;
+        for (int i = 0; i < numFiles; i++) {
+            String name = dis.readUTF();
+            int offset = dis.readInt();
+            int size = dis.readInt();
+            if (name.startsWith("*")) name = name.substring(1);
+            if (name.equals(target)) {
+                foundOffset = offset;
+                foundSize = size;
+            }
+        }
+        dis.close();
+
+        if (foundOffset == -1) {
+            System.err.println("File not found in archive: " + target);
+            System.exit(1);
+        }
+
+        RandomAccessFile raf = new RandomAccessFile(arcPath, "r");
+        raf.seek(foundOffset);
+        byte[] data = new byte[foundSize];
+        raf.readFully(data);
+        raf.close();
+        Files.write(Paths.get(outPath), data);
+        System.out.println("Extracted " + target + " (" + foundSize + " bytes) -> " + outPath);
+    }
+}