feat: add mobile application structure with emotion picker and API integration

- Added favicon and icon assets for the mobile app.
- Implemented EmotionPicker component for selecting emotions with child options.
- Created hooks for fetching emotions, feeds, and rapport data.
- Established API service for handling requests and authentication.
- Integrated Zustand for state management of user authentication.
- Defined color palette for the application.
- Set up TypeScript types for various entities including User, Emotion, and Feed.
- Configured Babel and TypeScript for the mobile project.
- Added package.json with necessary dependencies for Expo and React Native.

mobile/app/(tabs)/journal/_layout.tsx

@@ -0,0 +1,18 @@
+import { Stack } from 'expo-router';
+import { Colors } from '@/lib/colors';
+
+export default function JournalLayout() {
+  return (
+    <Stack
+      screenOptions={{
+        headerStyle: { backgroundColor: Colors.white },
+        headerTitleStyle: { fontWeight: '700', color: Colors.black },
+      }}
+    >
+      <Stack.Screen name="index" options={{ title: 'Mon journal' }} />
+      <Stack.Screen name="new" options={{ title: 'Nouvelle saisie', presentation: 'modal' }} />
+      <Stack.Screen name="edit" options={{ title: 'Modifier la saisie', presentation: 'modal' }} />
+      <Stack.Screen name="reports" options={{ title: 'Mes rapports' }} />
+    </Stack>
+  );
+}