feat(panic): FUCK [panic] mode=strict|fallback + realtest image variant

- UTSM panic_full returns in fallback mode (logs [PANIC:FALLBACK] + code + hit
  count); panic_halt keeps always-halt sites (CPU exception, VMM-E11 LA57,
  VMM-E15 DSK jump, UTSM-E42 test hook). Call sites given safe continuations.
- Mode passed to DSK/FirstInit/login/desktop via DSK_BOOT_FLAG_PANIC_FALLBACK;
  DKM kernel_api.panic / kern.log.panic return to driver; ext4 fatal aborts the
  op via setjmp/longjmp and DSK falls back to FAT32 ESP.
- build.ps1/Makefile: dev=strict, release=fallback, new realtest (release
  options + strict); default -Variant all; serialized iso packing under -j.
- Fix '*/' inside comments (dkm.h, kernel_api.h, bus.c) that broke the build.
- Includes pending work: dkm_bus service bus, mt7920/wlan drivers, desktop
  files/startmenu/prank, pe-tools, diskinfo, docs.

Co-authored-by: Cursor <cursoragent@cursor.com>

CODE/UTSM/kernel/net.c

@@ -106,18 +106,22 @@ static int net_connect_impl(u32 index, const char *ssid, const char *password) {
     if (index >= g_net_device_count) return -2;
     const dkm_net_device_desc *dev = &g_net_devices[index];
     /* 严格错误策略：无线设备未提供关联回调 = 驱动后端未实现，零降级 panic */
-    if (!dev->connect)
+    if (!dev->connect) {
         panic_full("NET-E20 WLAN CONNECT NOT SUPPORTED",
                    "wireless netdev has no connect backend (native chip driver pending)", 0);
+        return -3;
+    }
     return dev->connect(dev->ctx, ssid, password);
 }
 
 static int net_disconnect_impl(u32 index) {
     if (index >= g_net_device_count) return -2;
     const dkm_net_device_desc *dev = &g_net_devices[index];
-    if (!dev->disconnect)
+    if (!dev->disconnect) {
         panic_full("NET-E21 WLAN DISCONNECT NOT SUPPORTED",
                    "wireless netdev has no disconnect backend (native chip driver pending)", 0);
+        return -3;
+    }
     return dev->disconnect(dev->ctx);
 }