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/chair_interaction.tscn

@@ -0,0 +1,33 @@
+[gd_scene load_steps=3 format=3 uid="uid://dchair1nt0001a"]
+
+[ext_resource type="Script" path="res://scripts/character/chair_interaction.gd" id="1_chair"]
+
+[sub_resource type="BoxShape3D" id="Shape_Trigger"]
+size = Vector3(1.6, 2.0, 1.6)
+
+[node name="ChairInteraction" type="Area3D" node_paths=PackedStringArray("seat_transform_path")]
+script = ExtResource("1_chair")
+seat_transform_path = NodePath("SeatMarker")
+
+[node name="TriggerShape" type="CollisionShape3D" parent="."]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0)
+shape = SubResource("Shape_Trigger")
+
+[node name="SeatMarker" type="Marker3D" parent="."]
+transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0.35)
+
+[node name="PromptLayer" type="CanvasLayer" parent="."]
+
+[node name="PromptLabel" type="Label" parent="PromptLayer"]
+anchors_preset = 8
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = -100.0
+offset_top = 60.0
+offset_right = 100.0
+offset_bottom = 90.0
+horizontal_alignment = 1
+vertical_alignment = 1
+text = "Press E to sit"