P14-02: Split warps into guest FRONT and staff BACK service warp (A08)

The FRONT Mana warp is guest-only: its connectors carry the "!staff" access,
which path access checks treat as open to everyone except staff. A new 2x2
BACK service warp links only to other service warps for staff, with A07
values. Registry and palette now hold 25 definitions.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scenes/main/main.gd

@@ -48,6 +48,7 @@ const MVP_FACILITY_IDS: Array[StringName] = [
 	&"guest_stairs",
 	&"service_stairs",
 	&"mana_warp",
+	&"service_warp",
 	&"staff_door",
 	&"guest_corridor",
 	&"service_corridor",