feat(pets): replace static cats with Live2D LittleCat model (black texture)

- Copied LittleCat model files to frontend/public/live2d/models/little-cat/
- Using the black alternate texture as default
- Created Live2DCat component that renders the model in a small canvas
- PetZone now shows a single Live2D cat instead of two SVG cats

frontend/public/live2d/models/little-cat/LittleCat.model3.json

@@ -0,0 +1,29 @@
+{
+	"Version": 3,
+	"FileReferences": {
+		"Moc": "LittleCat.moc3",
+		"Textures": [
+			"LittleCat.2048/texture_00.png"
+		],
+		"Physics": "LittleCat.physics3.json",
+		"DisplayInfo": "LittleCat.cdi3.json"
+	},
+	"Groups": [
+		{
+			"Target": "Parameter",
+			"Name": "EyeBlink",
+			"Ids": [
+				"ParamEyeLOpen",
+				"ParamEyeROpen"
+			]
+		},
+		{
+			"Target": "Parameter",
+			"Name": "LipSync",
+			"Ids": [
+				"ParamMouthForm",
+				"ParamMouthOpenY"
+			]
+		}
+	]
+}