P14-02: Add buildable Mana warp (A07)

2x2 FRONT warp at 3000G/30 materials/360 min, 15G/day and 1 Mana upkeep.
Every completed warp pair is linked by one path connector, so crossing is a
single step; a 3-Mana fare per rider is charged once in the step's tick.
Warps close while either end is unpowered, the reserve is empty or below one
fare, and blocked arrivals offer no step. Saves validate the derived links.

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

scripts/world/path_service.gd

@@ -1420,6 +1420,15 @@ func has_connector(connector_id: StringName) -> bool:
 	return _connectors.has(connector_id)
 
 
+func get_connector_ids_with_prefix(prefix: String) -> Array[StringName]:
+	var ids: Array[StringName] = []
+	for connector_id: Variant in _connectors:
+		if String(connector_id).begins_with(prefix):
+			ids.append(StringName(connector_id))
+	ids.sort_custom(func(a: StringName, b: StringName) -> bool: return String(a) < String(b))
+	return ids
+
+
 func get_connector(connector_id: StringName) -> Dictionary:
 	if not _connectors.has(connector_id):
 		return {}