feat(title): TitleScreen composition, menu + selection, boot scene

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/scripts/ui/title/title_screen.gd

@@ -0,0 +1,95 @@
+class_name TitleScreen
+extends Control
+## The entry-point screen (mock Title Screen). Editor-first (ADR 0001): the whole
+## composition lives in TitleScreen.tscn; this script drives selection, input, and
+## dispatches the menu. §2: presentation/state — no AI here (the DM enters at the
+## shell). The atmosphere (bg shader, glow, embers) is layered on in a later task.
+
+signal menu_activated(id: StringName)
+
+const SHELL := "res://scenes/shell/MainWindowShell.tscn"
+
+var _rows: Array = []
+var _sel: int = 0
+
+@onready var _menu: VBoxContainer = $Content/Menu
+@onready var _footer_left: Label = $FooterLeft
+@onready var _background: ColorRect = $Background
+@onready var _rule: ColorRect = $Content/Rule
+
+
+func _ready() -> void:
+	# Root Control run via F6 is not sized by full-rect anchors — size explicitly.
+	_fit_to_viewport()
+	get_viewport().size_changed.connect(_fit_to_viewport)
+
+	_background.color = Palette.STAGE_1
+	_rule.color = Palette.GOLD
+
+	_rows = []
+	for row in _menu.get_children():
+		if row.has_meta("action"):
+			_rows.append(row)
+			(row.get_node("Marker") as Label).add_theme_color_override("font_color", Palette.GOLD)
+	_wire_row_mouse()
+
+	_footer_left.text = Version.new().footer()
+	menu_activated.connect(_on_menu_activated)
+	_update_selection()
+
+
+func _fit_to_viewport() -> void:
+	size = get_viewport_rect().size
+
+
+func _wire_row_mouse() -> void:
+	for i in range(_rows.size()):
+		var idx := i  # fresh per-iteration binding for the closures
+		var row: Control = _rows[idx]
+		row.mouse_entered.connect(func():
+			_sel = idx
+			_update_selection())
+		row.gui_input.connect(func(e: InputEvent):
+			if e is InputEventMouseButton and e.pressed and e.button_index == MOUSE_BUTTON_LEFT:
+				_activate(idx))
+
+
+func _unhandled_input(event: InputEvent) -> void:
+	if event.is_action_pressed("ui_down"):
+		_move(1)
+	elif event.is_action_pressed("ui_up"):
+		_move(-1)
+	elif event.is_action_pressed("ui_accept"):
+		_activate(_sel)
+
+
+func _move(delta: int) -> void:
+	if _rows.is_empty():
+		return
+	_sel = wrapi(_sel + delta, 0, _rows.size())
+	_update_selection()
+
+
+func _activate(i: int) -> void:
+	if i < 0 or i >= _rows.size():
+		return
+	menu_activated.emit(_rows[i].get_meta("action"))
+
+
+func _on_menu_activated(id: StringName) -> void:
+	match id:
+		&"new_game":
+			get_tree().change_scene_to_file(SHELL)
+		&"quit":
+			get_tree().quit()
+		_:
+			pass  # inert placeholder — the screen lands in a later milestone
+
+
+func _update_selection() -> void:
+	for i in range(_rows.size()):
+		var row: Control = _rows[i]
+		var selected := i == _sel
+		(row.get_node("Marker") as Label).modulate.a = 1.0 if selected else 0.0
+		var label := row.get_node("Body/Label") as Label
+		label.add_theme_color_override("font_color", Palette.CREAM_BRIGHT if selected else Palette.MUTED_MONO)