feat: Implement comprehensive PWA functionality

- Add full PWA configuration with manifest and service worker
- Create PWAInstallBanner component with mobile detection
- Implement install banner on login page (shows below login form)
- Add usePWA composable for reusable PWA functionality
- Configure offline support with Workbox caching strategies
- Add PWA initialization plugin
- Update app name to 'Port Nimara Portal' throughout
- Use circular logo in install banner and instructions
- Banner shows only once and hides if already installed
- Support both Android (direct install) and iOS (manual instructions)
- Add comprehensive documentation for PWA implementation

Features:
- Mobile-only install banner with dismissal tracking
- Standalone mode detection to hide banner when installed
- Platform-specific installation instructions
- Offline functionality with API caching
- Auto-updating service worker
- Native app-like experience when installed

docs/pwa-implementation.md

@@ -0,0 +1,117 @@
+# PWA Implementation Guide
+
+## Overview
+The Port Nimara Portal has been implemented as a Progressive Web App (PWA) to provide users with a native app-like experience on mobile devices.
+
+## Features Implemented
+
+### 1. PWA Configuration
+- **App Name**: Port Nimara Portal
+- **Short Name**: Port Nimara
+- **Theme Color**: #387bca (brand primary color)
+- **Background Color**: #ffffff
+- **Display Mode**: standalone
+- **Start URL**: /
+- **Icons**: Multiple sizes from 72x72 to 512x512 pixels
+
+### 2. Install Banner
+- **Location**: Login page, below the login form
+- **Behavior**: 
+  - Only shows on mobile devices
+  - Hidden if app is already installed (standalone mode)
+  - Shows only once (dismissal stored in localStorage)
+  - Animated slide-in with 1-second delay
+
+### 3. Installation Flow
+- **Android**: Direct browser install prompt
+- **iOS**: Step-by-step instructions modal
+- **Other browsers**: Fallback instructions
+
+### 4. Offline Support
+- **Service Worker**: Auto-updating with Workbox
+- **Caching**: Network-first for API calls, cache-first for assets
+- **Navigation Fallback**: Routes to home page when offline
+
+## Files Added/Modified
+
+### New Files
+- `components/PWAInstallBanner.vue` - Install banner component
+- `composables/usePWA.ts` - PWA functionality composable
+- `plugins/pwa.client.ts` - PWA initialization plugin
+- `docs/pwa-implementation.md` - This documentation
+
+### Modified Files
+- `nuxt.config.ts` - Added PWA configuration
+- `pages/login.vue` - Added install banner component
+
+## Configuration Details
+
+### PWA Module Settings
+```typescript
+pwa: {
+  registerType: 'autoUpdate',
+  manifest: {
+    name: 'Port Nimara Portal',
+    short_name: 'Port Nimara',
+    description: 'Port Nimara Client Portal - Manage your berth interests and expressions of interest',
+    theme_color: '#387bca',
+    background_color: '#ffffff',
+    display: 'standalone',
+    orientation: 'portrait',
+    start_url: '/',
+    scope: '/',
+    icons: [/* 8 icon sizes */]
+  },
+  workbox: {
+    // Caching strategies
+  }
+}
+```
+
+### Icon Requirements
+The following icon sizes are configured:
+- 72x72, 96x96, 128x128, 144x144 (Android)
+- 152x152, 192x192 (iOS, Android)
+- 384x384, 512x512 (Splash screens, large displays)
+
+All icons are located in `/public/icons/` and based on the circular Port Nimara logo.
+
+### Browser Support
+- **Chrome/Edge (Android)**: Full PWA support with install prompt
+- **Safari (iOS)**: Manual installation via "Add to Home Screen"
+- **Firefox**: Basic PWA support
+- **Other browsers**: Graceful degradation with instructions
+
+## Usage Instructions
+
+### For Users
+1. Visit the login page on a mobile device
+2. If eligible, an install banner will appear below the login form
+3. Tap "Install App" to begin installation
+4. Follow platform-specific instructions if needed
+
+### For Developers
+The PWA functionality is automatically initialized. Use the `usePWA()` composable to access PWA state:
+
+```typescript
+const { isInstalled, canInstall, install, isMobile, isIOS } = usePWA();
+```
+
+## Testing
+- Test on actual mobile devices for best results
+- Use Chrome DevTools > Application > Manifest to verify configuration
+- Check Service Worker registration in DevTools > Application > Service Workers
+- Test offline functionality by disabling network
+
+## Deployment Notes
+- Ensure HTTPS is enabled (required for PWA)
+- Icons must be accessible via direct URLs
+- Service worker will be auto-generated and registered
+- Manifest will be auto-generated from nuxt.config.ts settings
+
+## Future Enhancements
+- Push notifications
+- Background sync
+- App shortcuts
+- Share target functionality
+- Install banner in dashboard for non-mobile users