Standardize button labels and document UI states

Finish the button-label audit with a surface-by-surface table, clarify Quit
game vs Quit to menu, rename Apply to Apply settings, and use string-table
keys for the new labels. Extend the smoke checklist with UI copy/button checks.
Headless 250/250, docs check OK.

src/game/ui/settings_panel.gd

@@ -8,6 +8,7 @@ extends CanvasLayer
 
 const InputBindings := preload("res://src/core/input_bindings.gd")
 const UiArt := preload("res://src/game/ui/art.gd")
+const Strings := preload("res://src/core/strings.gd")
 
 signal applied(settings: Dictionary)
 signal replay_tutorial_requested()
@@ -169,7 +170,7 @@ func _build() -> void:
 
 	var save_button := Button.new()
 	save_button.name = "ApplyButton"
-	save_button.text = "Apply"
+	save_button.text = Strings.lookup("ui.apply_settings")
 	save_button.pressed.connect(_on_apply)
 	row.add_child(save_button)
 

src/game/ui/shift_review.gd

@@ -74,7 +74,7 @@ func _init() -> void:
 	center.add_child(restart)
 
 	var quit_btn := Button.new()
-	quit_btn.text = "Quit"
+	quit_btn.text = Strings.lookup("ui.quit_game")
 	quit_btn.pressed.connect(func(): get_tree().quit())
 	quit_btn.size_flags_horizontal = Control.SIZE_SHRINK_CENTER
 	_style_review_button(timeline)

src/game/ui/start_menu.gd

@@ -11,6 +11,7 @@ signal settings_requested()
 signal quit_requested()
 
 const UiArt := preload("res://src/game/ui/art.gd")
+const Strings := preload("res://src/core/strings.gd")
 
 const VENUES := [
 	{"id": "hollywood_building", "label": "Hollywood Boulevard", "blurb": "Building entrance, tourists and late-night trouble."},
@@ -142,7 +143,7 @@ func _build() -> void:
 
 	var quit_button := Button.new()
 	quit_button.name = "QuitButton"
-	quit_button.text = "Quit"
+	quit_button.text = Strings.lookup("ui.quit_game")
 	quit_button.pressed.connect(func(): quit_requested.emit())
 	row.add_child(quit_button)