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/system/usr/bin/bc250-cu-live-manager

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+exec /usr/share/bc250-40cu/vendor/bc250-cu-live-manager/bc250-cu-live-manager.sh "$@"

files/system/usr/bin/bc250-governor-profile

@@ -0,0 +1,162 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+CONFIG="/etc/cyan-skillfish-governor-smu/config.toml"
+BACKUP_DIR="/etc/cyan-skillfish-governor-smu/backups"
+LAST_BACKUP="/etc/cyan-skillfish-governor-smu/.bc250-40cu-last-backup"
+SERVICE="cyan-skillfish-governor-smu.service"
+
+usage() {
+  cat <<'EOF'
+BC-250 governor profile helper
+
+Usage:
+  bc250-governor-profile sweet-spot
+  bc250-governor-profile restore
+  bc250-governor-profile status
+
+Commands:
+  sweet-spot  Backup the current config and apply a 1500 MHz / 900 mV cap.
+  restore     Restore the last config backed up by this helper.
+  status      Show current governor config and service status.
+EOF
+}
+
+need_root() {
+  if [ "$(id -u)" != "0" ]; then
+    echo "ERROR: this command must run as root." >&2
+    exit 1
+  fi
+}
+
+restart_service() {
+  if systemctl list-unit-files "$SERVICE" >/dev/null 2>&1; then
+    systemctl restart "$SERVICE" || {
+      echo "WARN: could not restart $SERVICE. Check: systemctl status $SERVICE" >&2
+      return 1
+    }
+  fi
+}
+
+write_sweet_spot_config() {
+  cat > "$CONFIG" <<'EOF'
+# BC-250 40CU conservative profile.
+# Generated by bc250-governor-profile sweet-spot.
+# Target: 1500 MHz / 900 mV, based on bc250-40cu-unlock thermal guidance.
+
+[timing.intervals]
+sample = 250
+adjust = 100_000
+
+[gpu-usage]
+fix-metrics = true
+method = "busy-flag"
+flush-every = 10
+
+[gpu]
+set-method = "smu"
+
+[dbus]
+enabled = true
+
+[frequency-range]
+min = 1000
+max = 1500
+
+[timing.ramp-rates]
+normal = 1
+burst = 50
+
+[timing]
+burst-samples = 60
+down-events = 5
+
+[frequency-thresholds]
+adjust = 10
+
+[load-target]
+upper = 0.65
+lower = 0.50
+
+[temperature]
+throttling = 85
+throttling_recovery = 75
+
+[[safe-points]]
+frequency = 500
+voltage = 700
+
+[[safe-points]]
+frequency = 1000
+voltage = 800
+
+[[safe-points]]
+frequency = 1175
+voltage = 850
+
+[[safe-points]]
+frequency = 1500
+voltage = 900
+EOF
+}
+
+apply_sweet_spot() {
+  need_root
+  mkdir -p "$BACKUP_DIR" "$(dirname "$CONFIG")"
+
+  if [ -f "$CONFIG" ]; then
+    backup="$BACKUP_DIR/config.toml.$(date +%Y%m%d-%H%M%S).bak"
+    cp -a "$CONFIG" "$backup"
+    printf '%s\n' "$backup" > "$LAST_BACKUP"
+    echo "Backed up current governor config to $backup"
+  else
+    echo "No existing governor config found at $CONFIG; writing a new one."
+  fi
+
+  write_sweet_spot_config
+  echo "Applied BC-250 40CU sweet spot profile: 1500 MHz / 900 mV."
+  restart_service || true
+}
+
+restore_config() {
+  need_root
+
+  if [ ! -f "$LAST_BACKUP" ]; then
+    echo "ERROR: no backup marker found at $LAST_BACKUP." >&2
+    echo "Available backups:" >&2
+    ls -1 "$BACKUP_DIR"/config.toml.*.bak 2>/dev/null || true
+    exit 1
+  fi
+
+  backup="$(cat "$LAST_BACKUP")"
+  if [ ! -f "$backup" ]; then
+    echo "ERROR: backup no longer exists: $backup" >&2
+    exit 1
+  fi
+
+  cp -a "$backup" "$CONFIG"
+  echo "Restored governor config from $backup"
+  restart_service || true
+}
+
+show_status() {
+  if [ -f "$CONFIG" ]; then
+    echo "Governor config: $CONFIG"
+    grep -E '^(min|max|frequency|voltage|fix-metrics|method|set-method|throttling)' "$CONFIG" || true
+  else
+    echo "Governor config not found at $CONFIG"
+  fi
+  echo
+  systemctl status "$SERVICE" --no-pager || true
+}
+
+case "${1:-}" in
+  sweet-spot) apply_sweet_spot ;;
+  restore) restore_config ;;
+  status) show_status ;;
+  -h|--help|help|"") usage ;;
+  *)
+    usage >&2
+    exit 2
+    ;;
+esac