Add main menu, WebSocket API demo, and multi-scene game hub.

Replace the single-entry Pong flow with a menu launcher, a per-client API demo on :8081/ws with stream controls and tap flash feedback, and bump the viewport to 1920×1080.

Co-authored-by: Cursor <cursoragent@cursor.com>

scenes/demo.tscn

@@ -0,0 +1,166 @@
+[gd_scene format=3 uid="uid://clxuqui2bti65"]
+
+[ext_resource type="Script" path="res://scripts/demo.gd" id="1_demo"]
+
+[node name="Demo" type="Control"]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("1_demo")
+
+[node name="Background" type="ColorRect" parent="."]
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+mouse_filter = 2
+color = Color(0.08, 0.09, 0.14, 1)
+
+[node name="UiLayer" type="CanvasLayer" parent="."]
+
+[node name="TopBar" type="HBoxContainer" parent="UiLayer"]
+anchors_preset = 10
+anchor_right = 1.0
+offset_left = 16.0
+offset_top = 12.0
+offset_right = -16.0
+offset_bottom = 52.0
+grow_horizontal = 2
+theme_override_constants/separation = 16
+
+[node name="BackButton" type="Button" parent="UiLayer/TopBar"]
+custom_minimum_size = Vector2(100, 0)
+layout_mode = 2
+text = "Menü"
+
+[node name="Title" type="Label" parent="UiLayer/TopBar"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0.9, 0.92, 0.98, 1)
+theme_override_font_sizes/font_size = 22
+text = "API Demo"
+
+[node name="UrlLabel" type="Label" parent="UiLayer/TopBar"]
+layout_mode = 2
+size_flags_horizontal = 3
+theme_override_colors/font_color = Color(0.55, 0.6, 0.7, 1)
+theme_override_font_sizes/font_size = 13
+text = "ws://localhost:8081/ws"
+
+[node name="StatusLabel" type="Label" parent="UiLayer/TopBar"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0.75, 0.8, 0.9, 1)
+theme_override_font_sizes/font_size = 13
+text = "Verbinde…"
+
+[node name="MainSplit" type="HSplitContainer" parent="UiLayer"]
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+offset_left = 16.0
+offset_top = 60.0
+offset_right = -16.0
+offset_bottom = -12.0
+grow_horizontal = 2
+grow_vertical = 2
+split_offset = 520
+
+[node name="LeftPanel" type="VBoxContainer" parent="UiLayer/MainSplit"]
+layout_mode = 2
+size_flags_horizontal = 3
+size_flags_vertical = 3
+theme_override_constants/separation = 12
+
+[node name="Toolbar" type="HBoxContainer" parent="UiLayer/MainSplit/LeftPanel"]
+layout_mode = 2
+theme_override_constants/separation = 12
+
+[node name="ListClientsBtn" type="Button" parent="UiLayer/MainSplit/LeftPanel/Toolbar"]
+custom_minimum_size = Vector2(140, 40)
+layout_mode = 2
+text = "Clients laden"
+
+[node name="IntervalLabel" type="Label" parent="UiLayer/MainSplit/LeftPanel/Toolbar"]
+layout_mode = 2
+text = "interval_ms:"
+
+[node name="IntervalSpin" type="SpinBox" parent="UiLayer/MainSplit/LeftPanel/Toolbar"]
+custom_minimum_size = Vector2(90, 0)
+layout_mode = 2
+min_value = 1.0
+max_value = 10000.0
+value = 16.0
+
+[node name="ClientsScroll" type="ScrollContainer" parent="UiLayer/MainSplit/LeftPanel"]
+layout_mode = 2
+size_flags_vertical = 3
+horizontal_scroll_mode = 0
+
+[node name="ClientsList" type="VBoxContainer" parent="UiLayer/MainSplit/LeftPanel/ClientsScroll"]
+layout_mode = 2
+size_flags_horizontal = 3
+theme_override_constants/separation = 8
+
+[node name="EmptyHint" type="Label" parent="UiLayer/MainSplit/LeftPanel/ClientsScroll/ClientsList"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0.55, 0.6, 0.7, 1)
+theme_override_font_sizes/font_size = 13
+autowrap_mode = 3
+text = "„Clients laden“ drücken, pro Client Accel/Tap konfigurieren, dann Stream starten."
+
+[node name="StreamBar" type="HBoxContainer" parent="UiLayer/MainSplit/LeftPanel"]
+layout_mode = 2
+theme_override_constants/separation = 12
+
+[node name="StartStreamBtn" type="Button" parent="UiLayer/MainSplit/LeftPanel/StreamBar"]
+custom_minimum_size = Vector2(0, 48)
+layout_mode = 2
+size_flags_horizontal = 3
+theme_override_font_sizes/font_size = 16
+disabled = true
+text = "Stream starten"
+
+[node name="StopStreamBtn" type="Button" parent="UiLayer/MainSplit/LeftPanel/StreamBar"]
+custom_minimum_size = Vector2(0, 48)
+layout_mode = 2
+size_flags_horizontal = 3
+theme_override_font_sizes/font_size = 16
+disabled = true
+text = "Stream stoppen"
+
+[node name="LogPanel" type="VBoxContainer" parent="UiLayer/MainSplit"]
+layout_mode = 2
+size_flags_horizontal = 3
+size_flags_vertical = 3
+theme_override_constants/separation = 8
+
+[node name="LogHeader" type="Label" parent="UiLayer/MainSplit/LogPanel"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0.9, 0.92, 0.55, 1)
+theme_override_font_sizes/font_size = 14
+text = "Log"
+
+[node name="LogOutput" type="TextEdit" parent="UiLayer/MainSplit/LogPanel"]
+layout_mode = 2
+size_flags_vertical = 3
+theme_override_font_sizes/font_size = 12
+editable = false
+wrap_mode = 1
+
+[node name="StreamHeader" type="Label" parent="UiLayer/MainSplit/LogPanel"]
+layout_mode = 2
+theme_override_colors/font_color = Color(0.9, 0.92, 0.55, 1)
+theme_override_font_sizes/font_size = 14
+text = "Live-Daten (alle Clients)"
+
+[node name="StreamOutput" type="Label" parent="UiLayer/MainSplit/LogPanel"]
+custom_minimum_size = Vector2(0, 160)
+layout_mode = 2
+theme_override_colors/font_color = Color(0.75, 0.85, 0.95, 1)
+theme_override_font_sizes/font_size = 13
+autowrap_mode = 3
+text = "—"