sprint A cleanup: accessibility, signals, race, debris

G: large_text scales global theme font (14→20 at 1.4×) via new
GameState.get_font_scale + EventBus.settings_changed. reduce_motion
gates ResumeToast fade (HintOverlay already gated).

I: InspectTooltip long-press wired (500ms hold, 12px drift cancel,
tap-to-clear pin). Stale Phase 19 TODO replaced with accurate doc.

H: Pawn.arrived_at_destination now also emitted on
EventBus.pawn_arrived_at_destination; DirtinessSystem subscribes and
bumps indoor traffic dirt (BUMP_INDOOR_TRAFFIC = 0.2). Outdoor-tracked
bump needs Pawn.prev_tile — flagged for Phase 20.

P: CraftingProvider caches ingredient item ref on Job.ingredient_item;
JobRunner._tick_pickup validates is_instance_valid + not being_carried
before the tile scan, cancels cleanly if another pawn grabbed it.

J: rest_provider.gd deleted. Removed @onready + register call from
world.gd, ext_resource + node from world.tscn. Provider count comment
updated to 9.

M: DIRTY_THRESHOLD extracted — cleaning_provider and job_runner now
reference DirtinessSystem.DIRT_DIRTY_THRESHOLD.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scenes/pawn/pawn.gd

@@ -1139,6 +1139,7 @@ func _advance_walk() -> void:
 			_state_label.text = Strings.t(&"pawn.state.idle")
 			walk_completed.emit()
 			arrived_at_destination.emit(tile)
+			EventBus.pawn_arrived_at_destination.emit(self, tile)
 			Audit.log("pawn", "%s arrived at %s" % [pawn_name, tile])