Add MSX2J ROM and update manifests

Add MSX2J.rom (sha1: 0081ea0d25bc5cd8d70b60ad8cfdc7307812c0fd, size: 32768) to multiple install manifests and the RetroDECK bios list. Update generated timestamps and adjust total_files/total_size counts in batocera, lakka, recalbox, retroarch, retrobat, and retrodeck manifests. Also bump README verified file count and regenerate the auto-generated timestamp to reflect the new entry.

install/lakka.json

@@ -4,7 +4,7 @@
   "platform": "lakka",
   "display_name": "Lakka",
   "version": "1.0",
-  "generated": "2026-04-01T14:42:08Z",
+  "generated": "2026-04-02T08:32:35Z",
   "base_destination": "system",
   "detect": [
     {
@@ -15,8 +15,8 @@
     }
   ],
   "standalone_copies": [],
-  "total_files": 1620,
-  "total_size": 5255358024,
+  "total_files": 1621,
+  "total_size": 5255390792,
   "files": [
     {
       "dest": "3do_arcade_saot.bin",
@@ -3438,6 +3438,15 @@
         "blueMSX"
       ]
     },
+    {
+      "dest": "Machines/Shared Roms/MSX2J.rom",
+      "sha1": "0081ea0d25bc5cd8d70b60ad8cfdc7307812c0fd",
+      "size": 32768,
+      "repo_path": "bios/Microsoft/MSX/.variants/MSX2.ROM.0081ea0d",
+      "cores": [
+        "blueMSX"
+      ]
+    },
     {
       "dest": "Machines/Shared Roms/MSX2R2.ROM",
       "sha1": "ebb7eb540a390509edfd36c84288ba85e63f2d1f",