feat(core): implement room navigation, character states, save/load and settings menu

- RoomNavigator autoload: smooth camera pan between floors
- Floor1 and Floor2 placeholder rooms with elevator buttons
- CharacterData Resource with State enum (HEALTHY/SICK/SLEEPING/TIRED)
- Character visual state feedback via ColorRect color
- Main scene loads saved state on startup
- SettingsMenu with music/sfx sliders and game reset
- HUD settings button to open SettingsMenu

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

scenes/ui/SettingsMenu.tscn

@@ -0,0 +1,103 @@
+[gd_scene load_steps=2 format=3 uid="uid://cozypaw_settings"]
+
+[ext_resource type="Script" path="res://scripts/systems/settings_menu.gd" id="1_settings"]
+
+[node name="SettingsMenu" type="CanvasLayer"]
+script = ExtResource("1_settings")
+visible = false
+
+[node name="Backdrop" type="ColorRect" parent="."]
+color = Color(0, 0, 0, 0.7)
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 1.0
+anchor_bottom = 1.0
+offset_left = 0.0
+offset_top = 0.0
+offset_right = 0.0
+offset_bottom = 0.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="Panel" type="Panel" parent="."]
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = -200.0
+offset_top = -150.0
+offset_right = 200.0
+offset_bottom = 150.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="Title" type="Label" parent="Panel"]
+offset_left = 0.0
+offset_top = 16.0
+offset_right = 400.0
+offset_bottom = 64.0
+horizontal_alignment = 1
+text = "⚙"
+theme_override_font_sizes/font_size = 32
+
+[node name="MusicLabel" type="Label" parent="Panel"]
+offset_left = 24.0
+offset_top = 76.0
+offset_right = 80.0
+offset_bottom = 108.0
+text = "♪"
+theme_override_font_sizes/font_size = 24
+
+[node name="MusicSlider" type="HSlider" parent="Panel"]
+min_value = 0.0
+max_value = 1.0
+step = 0.05
+value = 0.6
+offset_left = 88.0
+offset_top = 76.0
+offset_right = 376.0
+offset_bottom = 108.0
+
+[node name="SfxLabel" type="Label" parent="Panel"]
+offset_left = 24.0
+offset_top = 120.0
+offset_right = 80.0
+offset_bottom = 152.0
+text = "🔊"
+theme_override_font_sizes/font_size = 24
+
+[node name="SfxSlider" type="HSlider" parent="Panel"]
+min_value = 0.0
+max_value = 1.0
+step = 0.05
+value = 1.0
+offset_left = 88.0
+offset_top = 120.0
+offset_right = 376.0
+offset_bottom = 152.0
+
+[node name="ResetButton" type="Button" parent="Panel"]
+offset_left = 24.0
+offset_top = 172.0
+offset_right = 88.0
+offset_bottom = 236.0
+text = "↺"
+theme_override_font_sizes/font_size = 28
+
+[node name="ResetConfirmDialog" type="ConfirmationDialog" parent="Panel"]
+title = "Reset?"
+dialog_text = "Spielstand löschen?"
+
+[node name="CloseButton" type="Button" parent="Panel"]
+offset_left = 312.0
+offset_top = 172.0
+offset_right = 376.0
+offset_bottom = 236.0
+text = "✕"
+theme_override_font_sizes/font_size = 28
+
+[connection signal="value_changed" from="Panel/MusicSlider" to="." method="_on_music_slider_value_changed"]
+[connection signal="value_changed" from="Panel/SfxSlider" to="." method="_on_sfx_slider_value_changed"]
+[connection signal="pressed" from="Panel/ResetButton" to="." method="_on_reset_button_pressed"]
+[connection signal="confirmed" from="Panel/ResetConfirmDialog" to="." method="_on_reset_confirmed"]
+[connection signal="pressed" from="Panel/CloseButton" to="." method="_on_close_button_pressed"]