feat(client): hub teleport UX — Home key, fade transition (#501)

Home key sends TeleportToHub in Gauntlet mode. Camera snaps to hub
spawn with 0.3s fade-from-black. Clears dialogue/monologue buffers
on teleport. Teleport detection uses distance threshold (>5 tiles)
so future teleport types get the transition for free.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/input_mapper.gd

@@ -20,6 +20,7 @@ enum Action {
 	TOGGLE_STANCE_UP, TOGGLE_STANCE_DOWN,
 	BUG_REPORT,  # #495: F12 WRONG button — client-only, not sent to server
 	SET_FACING,  # D-054: facing octant update (no movement)
+	TELEPORT_HUB,  # #501: Home key — teleport to hub (Gauntlet-only)
 }
 
 var input_queue: Array[Dictionary] = []
@@ -105,6 +106,9 @@ func _unhandled_input(event: InputEvent) -> void:
 		action = Action.TOGGLE_STANCE_DOWN
 	elif event.is_action_pressed("bug_report"):
 		action = Action.BUG_REPORT
+	elif event.is_action_pressed("teleport_hub"):
+		if GameState.gauntlet_mode:
+			action = Action.TELEPORT_HUB
 
 	if action != -1:
 		input_queue.append({