feat(poc): implement Sprint 1 proof of concept

- project.godot with autoload configuration
- Reception room with placeholder visuals
- Draggable Character with DragDropComponent
- Interactive flower object with bounce animation
- GameState, SaveManager, AudioManager, InputManager autoloads
- HUD with back button and music toggle

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scenes/ui/HUD.tscn

@@ -0,0 +1,35 @@
+[gd_scene load_steps=2 format=3 uid="uid://cozypaw_hud"]
+
+[ext_resource type="Script" path="res://scripts/systems/hud.gd" id="1_hud"]
+
+[node name="HUD" type="CanvasLayer"]
+script = ExtResource("1_hud")
+
+[node name="BackButton" type="Button" parent="."]
+anchors_preset = 0
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+offset_left = 16.0
+offset_top = 16.0
+offset_right = 80.0
+offset_bottom = 80.0
+text = "←"
+flat = false
+
+[node name="MusicToggle" type="Button" parent="."]
+anchors_preset = 1
+anchor_left = 1.0
+anchor_top = 0.0
+anchor_right = 1.0
+anchor_bottom = 0.0
+offset_left = -80.0
+offset_top = 16.0
+offset_right = -16.0
+offset_bottom = 80.0
+text = "♪"
+flat = false
+
+[connection signal="pressed" from="BackButton" to="." method="_on_back_button_pressed"]
+[connection signal="pressed" from="MusicToggle" to="." method="_on_music_toggle_pressed"]