feat: add domain models and repositories for user, spool presets, and filaments

- Introduced SpoolPreset and User domain models with necessary DTOs and utility functions.
- Created AuthRepository, FilamentRepository, and SpoolPresetRepository interfaces for authentication and data management.
- Implemented UI components for filament display, including ColorSwatch, FilamentCard, and StockBar.
- Developed layout components such as Header and Screen for consistent app structure.
- Added reusable UI components like Badge, Button, Card, and Input for better user interaction.
- Established global constants and theme settings for consistent styling across the application.
- Implemented utility functions for filament calculations and formatting.
- Created Zustand stores for managing authentication, filament, and preset states.
- Configured TypeScript settings for improved development experience.

mobile/app/(app)/_layout.tsx

@@ -0,0 +1,8 @@
+import React from 'react';
+import { Stack } from 'expo-router';
+
+export default function AppLayout(): React.ReactElement {
+  return (
+    <Stack screenOptions={{ headerShown: false, contentStyle: { backgroundColor: '#1E1B18' } }} />
+  );
+}