fix: add jsdos.json to bundle for proper js-dos v8 config

The missing piece — dos.zone's bundle has .jsdos/jsdos.json
which tells js-dos v8 how to configure the emulator (autoexec
command, autolock=true, etc.). Without it, js-dos may apply
different defaults that don't match our dosbox.conf.

Also simplified dosbox.conf to just the essential sections
and removed mapperfile=mapper-jsdos.map (not bundled).
Keeps usescancodes=true, autolock=true, SB16 audio.

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

@@ -91,6 +91,7 @@ public class UploadResource {
                 String relExe = Path.of(mainExe).getFileName().toString();
                 String conf = buildDosboxConf(relExe);
                 Files.writeString(jsdos.resolve("dosbox.conf"), conf);
+                Files.write(jsdos.resolve("jsdos.json"), buildJsdosJson(relExe));
                 bundleFile = ".jsdos/dosbox.conf";
             } else {
                 // Create .jsdos bundle (flat in games dir)
@@ -218,6 +219,7 @@ public class UploadResource {
             String relExe = Path.of(mainExe).getFileName().toString();
             String conf = buildDosboxConf(relExe);
             Files.writeString(jsdos.resolve("dosbox.conf"), conf);
+            Files.write(jsdos.resolve("jsdos.json"), buildJsdosJson(relExe));
 
             // ZIP it up
             try (var zos = new java.util.zip.ZipOutputStream(Files.newOutputStream(bundlePath))) {
@@ -240,95 +242,49 @@ public class UploadResource {
     // ─── File Utilities ──────────────────────────────────────────
 
     /**
-     * Build a complete dosbox.conf with all sections needed for proper
-     * keyboard and hardware emulation in js-dos v8.
+     * Build a minimal dosbox.conf with the critical settings for js-dos v8.
+     * The key setting is usescancodes=true — without it DOSBox doesn't
+     * translate physical key presses into game input.
      */
+    private byte[] buildJsdosJson(String relExe) {
+        String json = "{"
+            + "\"autoexec\":{"
+            + "\"options\":{\"script\":{\"value\":\"" + escapeJson(relExe) + "\"}}"
+            + "},"
+            + "\"output\":{"
+            + "\"options\":{\"autolock\":{\"value\":true}}}"
+            + "}";
+        return json.getBytes(java.nio.charset.StandardCharsets.UTF_8);
+    }
+
+    private String escapeJson(String s) {
+        return s.replace("\\", "\\\\").replace("\"", "\\\"");
+    }
+
     private String buildDosboxConf(String relExe) {
         return "[sdl]\n"
             + "autolock=true\n"
-            + "fullscreen=false\n"
-            + "fulldouble=false\n"
-            + "fullresolution=original\n"
-            + "windowresolution=original\n"
-            + "output=surface\n"
-            + "sensitivity=100\n"
-            + "waitonerror=true\n"
-            + "priority=higher,normal\n"
-            + "mapperfile=mapper-jsdos.map\n"
             + "usescancodes=true\n"
-            + "\n"
-            + "[dosbox]\n"
-            + "machine=svga_s3\n"
-            + "memsize=16\n"
+            + "output=surface\n"
             + "\n"
             + "[cpu]\n"
             + "core=auto\n"
-            + "cputype=auto\n"
             + "cycles=auto\n"
             + "\n"
             + "[mixer]\n"
             + "nosound=false\n"
             + "rate=44100\n"
-            + "blocksize=1024\n"
-            + "prebuffer=20\n"
-            + "\n"
-            + "[render]\n"
-            + "frameskip=0\n"
-            + "aspect=false\n"
-            + "scaler=none\n"
-            + "\n"
-            + "[midi]\n"
-            + "mpu401=intelligent\n"
-            + "mididevice=default\n"
-            + "midiconfig=\n"
             + "\n"
             + "[sblaster]\n"
             + "sbtype=sb16\n"
-            + "sbbase=220\n"
             + "irq=7\n"
             + "dma=1\n"
             + "hdma=5\n"
-            + "sbmixer=true\n"
-            + "oplmode=auto\n"
-            + "oplemu=default\n"
-            + "oplrate=44100\n"
-            + "\n"
-            + "[gus]\n"
-            + "gus=false\n"
-            + "gusrate=44100\n"
-            + "gusbase=240\n"
-            + "gusirq=5\n"
-            + "gusdma=3\n"
-            + "ultradir=C:\\ULTRASND\n"
-            + "\n"
-            + "[speaker]\n"
-            + "pcspeaker=true\n"
-            + "pcrate=44100\n"
-            + "tandy=auto\n"
-            + "tandyrate=44100\n"
-            + "disney=true\n"
-            + "\n"
-            + "[joystick]\n"
-            + "joysticktype=auto\n"
-            + "timed=true\n"
-            + "autofire=false\n"
-            + "swap34=false\n"
-            + "buttonwrap=false\n"
-            + "\n"
-            + "[serial]\n"
-            + "serial1=dummy\n"
-            + "serial2=dummy\n"
-            + "serial3=disabled\n"
-            + "serial4=disabled\n"
             + "\n"
             + "[dos]\n"
             + "xms=true\n"
             + "ems=true\n"
             + "umb=true\n"
-            + "keyboardlayout=auto\n"
-            + "\n"
-            + "[ipx]\n"
-            + "ipx=true\n"
             + "\n"
             + "[autoexec]\n"
             + "@echo off\n"