Move screen designs to the runtime root and add the UI art loader

- screen_designs.py now reads/writes assets/images/ui/ (ADR-0014); docs/
  screens/designs/ stays the reference-only snapshot, documented as historical
- add src/game/ui/art.gd: cached loader for assets/images/ui|scenes with null
  fallbacks for missing files, plus headless tests
- start menu uses the start_menu scene art as a full-screen backdrop, covers the
  baked-in mockup panel with an opaque panel, and styles the venue rows to match
- update README/architecture/TODO path notes and mark the storage/code-path/loader
  items done; DONE records the historical path move
- compare still 11 good / 0 bad; headless 226/226

README/PLAN realism-pass edits from another workstream remain unstaged." && git log --oneline -1

src/game/ui/art.gd

@@ -0,0 +1,53 @@
+class_name UiArt
+extends RefCounted
+## Central loader for runtime interface/scene art (ADR-0014).
+##
+## Art lives under `assets/images/ui/` (composed screens) and
+## `assets/images/scenes/` (full-frame scene art). Missing files are a normal
+## state: callers get null and fall back to their procedural UI instead of
+## failing to load a screen.
+
+const ROOT := "res://assets/images/"
+const DIRECTORIES := ["ui", "scenes"]
+
+var _cache := {}
+
+## Load a named PNG, trying `ui/` first and then `scenes/`. Returns null when
+## the image is absent or not imported yet.
+func texture(art_name: String) -> Texture2D:
+	if art_name.strip_edges() == "":
+		return null
+	if _cache.has(art_name):
+		return _cache[art_name]
+	for directory in DIRECTORIES:
+		var path := ROOT + str(directory) + "/" + art_name + ".png"
+		if not ResourceLoader.exists(path):
+			continue
+		var loaded := ResourceLoader.load(path)
+		if loaded is Texture2D:
+			_cache[art_name] = loaded
+			return loaded
+	_cache[art_name] = null
+	return null
+
+func has(art_name: String) -> bool:
+	return texture(art_name) != null
+
+## Load an explicit relative path under `assets/images/`, for art whose screen
+## name does not follow the simple `<name>.png` convention.
+func texture_at(relative_path: String) -> Texture2D:
+	if relative_path.strip_edges() == "":
+		return null
+	var path := ROOT + relative_path.trim_prefix("/")
+	if _cache.has(path):
+		return _cache[path]
+	if not ResourceLoader.exists(path):
+		_cache[path] = null
+		return null
+	var loaded := ResourceLoader.load(path)
+	var result := loaded as Texture2D
+	_cache[path] = result
+	return result
+
+func clear_cache() -> void:
+	_cache.clear()

src/game/ui/start_menu.gd

@@ -8,6 +8,8 @@ signal venue_selected(scenario_id: String)
 signal settings_requested()
 signal quit_requested()
 
+const UiArt := preload("res://src/game/ui/art.gd")
+
 const VENUES := [
 	{"id": "hollywood_building", "label": "Hollywood Boulevard", "blurb": "Building entrance, tourists and late-night trouble."},
 	{"id": "joke_shop", "label": "The Joke Shop", "blurb": "Guest list, IDs and wand screening."},
@@ -30,11 +32,39 @@ func _build() -> void:
 	_root.mouse_filter = Control.MOUSE_FILTER_STOP
 	add_child(_root)
 
-	var bg := ColorRect.new()
-	bg.color = Color(0.03, 0.04, 0.07, 0.96)
-	bg.set_anchors_preset(Control.PRESET_FULL_RECT)
-	bg.mouse_filter = Control.MOUSE_FILTER_IGNORE
-	_root.add_child(bg)
+	var art := UiArt.new()
+	var backdrop_texture := art.texture("start_menu")
+	if backdrop_texture != null:
+		var backdrop := TextureRect.new()
+		backdrop.name = "MenuArt"
+		backdrop.texture = backdrop_texture
+		backdrop.expand_mode = TextureRect.EXPAND_IGNORE_SIZE
+		backdrop.stretch_mode = TextureRect.STRETCH_KEEP_ASPECT_COVERED
+		backdrop.set_anchors_preset(Control.PRESET_FULL_RECT)
+		backdrop.mouse_filter = Control.MOUSE_FILTER_IGNORE
+		_root.add_child(backdrop)
+		# The mockup includes its own title/buttons; cover that panel with an
+		# opaque rounded panel and keep the real controls on top.
+		var panel := ColorRect.new()
+		panel.name = "MenuPanel"
+		panel.color = Color(0.075, 0.08, 0.095, 1.0)
+		panel.set_anchor(SIDE_LEFT, 0.148)
+		panel.set_anchor(SIDE_TOP, 0.061)
+		panel.set_anchor(SIDE_RIGHT, 0.781)
+		panel.set_anchor(SIDE_BOTTOM, 0.921)
+		panel.mouse_filter = Control.MOUSE_FILTER_IGNORE
+		_root.add_child(panel)
+		var dim := ColorRect.new()
+		dim.color = Color(0.02, 0.03, 0.05, 0.18)
+		dim.set_anchors_preset(Control.PRESET_FULL_RECT)
+		dim.mouse_filter = Control.MOUSE_FILTER_IGNORE
+		_root.add_child(dim)
+	else:
+		var bg := ColorRect.new()
+		bg.color = Color(0.03, 0.04, 0.07, 0.96)
+		bg.set_anchors_preset(Control.PRESET_FULL_RECT)
+		bg.mouse_filter = Control.MOUSE_FILTER_IGNORE
+		_root.add_child(bg)
 
 	var center := CenterContainer.new()
 	center.set_anchors_preset(Control.PRESET_FULL_RECT)
@@ -66,6 +96,7 @@ func _build() -> void:
 		button.alignment = HORIZONTAL_ALIGNMENT_LEFT
 		button.custom_minimum_size = Vector2(460, 62)
 		button.pressed.connect(_on_venue_pressed.bind(i))
+		_style_venue_button(button)
 		column.add_child(button)
 		_buttons.append(button)
 
@@ -98,6 +129,35 @@ func _build() -> void:
 
 	_focus_index(0)
 
+## Match the dark, rounded rows in the `start_menu` mockup.
+func _style_venue_button(button: Button) -> void:
+	button.add_theme_font_size_override("font_size", 18)
+	button.add_theme_color_override("font_color", Color(0.94, 0.94, 0.92))
+	button.add_theme_color_override("font_hover_color", Color.WHITE)
+	var normal := StyleBoxFlat.new()
+	normal.bg_color = Color(0.115, 0.125, 0.15, 0.96)
+	normal.corner_radius_top_left = 12
+	normal.corner_radius_top_right = 12
+	normal.corner_radius_bottom_left = 12
+	normal.corner_radius_bottom_right = 12
+	normal.content_margin_left = 22
+	normal.content_margin_right = 22
+	normal.content_margin_top = 10
+	normal.content_margin_bottom = 10
+	var hover := normal.duplicate() as StyleBoxFlat
+	hover.bg_color = Color(0.16, 0.175, 0.21, 0.98)
+	var focus := normal.duplicate() as StyleBoxFlat
+	focus.bg_color = Color(0.14, 0.155, 0.19, 0.98)
+	focus.border_color = Color(0.85, 0.86, 0.88)
+	focus.border_width_left = 2
+	focus.border_width_top = 2
+	focus.border_width_right = 2
+	focus.border_width_bottom = 2
+	button.add_theme_stylebox_override("normal", normal)
+	button.add_theme_stylebox_override("hover", hover)
+	button.add_theme_stylebox_override("focus", focus)
+	button.add_theme_stylebox_override("pressed", hover)
+
 func _focus_index(i: int) -> void:
 	if _buttons.is_empty():
 		return

src/test/tests/test_ui_art.gd

@@ -0,0 +1,38 @@
+extends RefCounted
+## Headless tests for the runtime image loader (ADR-0014).
+
+const UiArt := preload("res://src/game/ui/art.gd")
+
+func test_loads_runtime_ui_art() -> bool:
+	var art := UiArt.new()
+	var start := art.texture("start_menu")
+	var venue := art.texture("venue_overview")
+	var a := TestUtils.check(start != null, "start_menu art loads from assets/images/ui")
+	var b := TestUtils.check(venue != null, "venue_overview art loads from assets/images/ui")
+	var c := TestUtils.check(art.has("start_menu"), "has() sees the runtime art")
+	return a and b and c
+
+func test_missing_art_returns_null() -> bool:
+	var art := UiArt.new()
+	var missing := art.texture("does_not_exist")
+	var empty := art.texture("")
+	var a := TestUtils.check(missing == null, "missing art returns null for a fallback")
+	var b := TestUtils.check(empty == null, "empty name returns null")
+	return a and b
+
+func test_explicit_relative_path() -> bool:
+	var art := UiArt.new()
+	var texture := art.texture_at("ui/start_menu.png")
+	var missing := art.texture_at("ui/nope.png")
+	var a := TestUtils.check(texture != null, "texture_at loads an explicit path")
+	var b := TestUtils.check(missing == null, "texture_at returns null when absent")
+	return a and b
+
+func test_cache_returns_the_same_resource() -> bool:
+	var art := UiArt.new()
+	var first := art.texture("start_menu")
+	var second := art.texture("start_menu")
+	var a := TestUtils.check(first != null and first == second, "textures are cached")
+	art.clear_cache()
+	var b := TestUtils.check(art.texture("start_menu") != null, "cache can be cleared")
+	return a and b