BC-250 console image: custom GNOME recipe with remote admin

Based on 62fixolab/Latest-Bazzite-AMD-BC-250-Patched-Images @ 347fd4d.

Adds on top of the fork:
- recipes/bc250-console-gnome.yml: governor + gnome-remote-desktop +
  openssh-server, sshd enabled, hhd.service masked, no signing module
  (local build + ISO path)
- files/console/usr/bin/bc250-remote-setup: one-time on-box SSH/RDP setup
- files/console/usr/lib/bootc/kargs.d/50-bc250-ttm.toml: ttm memory kargs
- BUILD-CONSOLE.md: build -> ISO -> validation instructions

files/console/ is separate from files/system/ so the 40-CU unlock tooling
stays out of this stable 24-CU image.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

files/justfiles/bc250-40cu.just

@@ -0,0 +1,30 @@
+# BC-250 40CU helper commands.
+
+bc250-cu-status:
+    @sudo bc250-cu-live-manager status
+
+bc250-cu-menu:
+    @sudo bc250-cu-live-manager menu
+
+bc250-cu-dry-run-40:
+    @sudo bc250-cu-live-manager --dry-run enable all
+
+bc250-cu-enable-40:
+    @sudo bc250-cu-live-manager enable all
+
+bc250-cu-save-boot:
+    @sudo bc250-cu-live-manager write-service-table
+    @sudo test -f /etc/bc250-cu-live-manager.conf || (echo "No saved 40CU boot table found; run ujust bc250-cu-menu or ujust bc250-cu-enable-40 first." >&2; exit 1)
+    @sudo bc250-cu-live-manager install-service
+
+bc250-cu-restore-24:
+    @sudo bc250-cu-live-manager stock-dispatch
+
+bc250-cu-disable-boot:
+    @sudo bc250-cu-live-manager uninstall-service
+
+bc250-cu-sweet-spot:
+    @sudo bc250-governor-profile sweet-spot
+
+bc250-cu-governor-restore:
+    @sudo bc250-governor-profile restore