dev: promote DOSBox-X and remove QEMU support

.gitignore

@@ -1,23 +1,9 @@
-# QEMU runtime state, downloaded media, and generated captures
-.qemu/*
-!.qemu/*.ps1
-!.qemu/*.mjs
-!.qemu/*.txt
-!.qemu/share/
-!.qemu/share/*.c
-.qemu/share/fec/
+# Legacy local QEMU state is no longer used, but may contain large user-owned images.
+.qemu/
 
 # Reproducible DOSBox-X/Open Watcom development cache and ephemeral runs
 .dosboxx/
 
-.qemu/*.qcow2
-.qemu/*.img
-.qemu/*.iso
-.qemu/*.zip
-.qemu/*.png
-.qemu/*.ppm
-.qemu/*.tmp
-
 # Windows reserved-device artifact: `> nul` under Git Bash creates a real file.
 # Committing it breaks checkout on Windows.
 nul
@@ -39,6 +25,3 @@ __pycache__/
 node_modules/
 .npm/
 .cache/
-
-# Temporary DOS build sources
-.qemu/share/dosag*.c