feat: Implement nausea symptom system and related features

- Added SymptomManager autoload for managing symptom intensities.
- Introduced nausea tilt effect for camera roll based on nausea intensity.
- Created color desaturation shader and overlay for visual feedback.
- Developed TreatmentManager to handle nausea ramping during IV treatment.
- Added hospital room scene with first-person controller and interactions.
- Implemented sit-down interaction for the treatment chair.
- Created IV insertion sequence with animations and completion signal.
- Added player controller with movement and interaction capabilities.
- Integrated nausea effects into the player experience with smooth transitions.

scenes/hospital/iv_insertion.tscn

@@ -0,0 +1,46 @@
+[gd_scene load_steps=8 format=3 uid="uid://div1nsert0001a"]
+
+[ext_resource type="Script" path="res://scripts/character/iv_insertion.gd" id="1_iv"]
+
+[sub_resource type="StandardMaterial3D" id="Mat_Skin"]
+albedo_color = Color(0.82, 0.64, 0.55, 1)
+roughness = 0.7
+
+[sub_resource type="StandardMaterial3D" id="Mat_Needle"]
+albedo_color = Color(0.85, 0.86, 0.9, 1)
+metallic = 0.8
+roughness = 0.2
+
+[sub_resource type="StandardMaterial3D" id="Mat_Tape"]
+albedo_color = Color(0.95, 0.93, 0.85, 1)
+roughness = 0.9
+
+[sub_resource type="BoxMesh" id="Mesh_Forearm"]
+size = Vector3(0.4, 0.08, 0.1)
+
+[sub_resource type="CylinderMesh" id="Mesh_Needle"]
+top_radius = 0.004
+bottom_radius = 0.004
+height = 0.12
+
+[sub_resource type="BoxMesh" id="Mesh_Tape"]
+size = Vector3(0.08, 0.005, 0.06)
+
+[node name="IVInsertion" type="Node3D" node_paths=PackedStringArray()]
+script = ExtResource("1_iv")
+
+[node name="Arm" type="Node3D" parent="."]
+
+[node name="Forearm" type="MeshInstance3D" parent="Arm"]
+mesh = SubResource("Mesh_Forearm")
+surface_material_override/0 = SubResource("Mat_Skin")
+
+[node name="Needle" type="MeshInstance3D" parent="Arm"]
+transform = Transform3D(1, 0, 0, 0, 0, -1, 0, 1, 0, 0.05, 0.12, 0)
+mesh = SubResource("Mesh_Needle")
+surface_material_override/0 = SubResource("Mat_Needle")
+
+[node name="Tape" type="MeshInstance3D" parent="Arm"]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0.05, 0.045, 0)
+mesh = SubResource("Mesh_Tape")
+surface_material_override/0 = SubResource("Mat_Tape")