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

composables/usePWA.ts

@@ -0,0 +1,101 @@
+export const usePWA = () => {
+  const isInstalled = ref(false);
+  const isInstallable = ref(false);
+  const deferredPrompt = ref<any>(null);
+
+  // Check if app is installed (running in standalone mode)
+  const checkInstallStatus = () => {
+    if (process.client) {
+      isInstalled.value = window.matchMedia('(display-mode: standalone)').matches ||
+                          (window.navigator as any).standalone ||
+                          document.referrer.includes('android-app://');
+    }
+  };
+
+  // Check if device is mobile
+  const isMobile = computed(() => {
+    if (process.client) {
+      return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
+    }
+    return false;
+  });
+
+  // Check if device is iOS
+  const isIOS = computed(() => {
+    if (process.client) {
+      return /iPad|iPhone|iPod/.test(navigator.userAgent);
+    }
+    return false;
+  });
+
+  // Check if device is Android
+  const isAndroid = computed(() => {
+    if (process.client) {
+      return /Android/i.test(navigator.userAgent);
+    }
+    return false;
+  });
+
+  // Install the app
+  const install = async () => {
+    if (deferredPrompt.value) {
+      deferredPrompt.value.prompt();
+      const choiceResult = await deferredPrompt.value.userChoice;
+      
+      if (choiceResult.outcome === 'accepted') {
+        console.log('User accepted the install prompt');
+        deferredPrompt.value = null;
+        isInstallable.value = false;
+        return true;
+      } else {
+        console.log('User dismissed the install prompt');
+        return false;
+      }
+    }
+    return false;
+  };
+
+  // Check if app can be installed
+  const canInstall = computed(() => {
+    return isMobile.value && !isInstalled.value && (isInstallable.value || isIOS.value);
+  });
+
+  // Initialize PWA functionality
+  const init = () => {
+    if (process.client) {
+      checkInstallStatus();
+
+      // Listen for the beforeinstallprompt event
+      window.addEventListener('beforeinstallprompt', (e) => {
+        console.log('beforeinstallprompt event fired');
+        e.preventDefault();
+        deferredPrompt.value = e;
+        isInstallable.value = true;
+      });
+
+      // Listen for successful app installation
+      window.addEventListener('appinstalled', () => {
+        console.log('PWA was installed');
+        isInstalled.value = true;
+        isInstallable.value = false;
+        deferredPrompt.value = null;
+      });
+
+      // Listen for display mode changes
+      window.matchMedia('(display-mode: standalone)').addEventListener('change', (e) => {
+        isInstalled.value = e.matches;
+      });
+    }
+  };
+
+  return {
+    isInstalled: readonly(isInstalled),
+    isInstallable: readonly(isInstallable),
+    isMobile,
+    isIOS,
+    isAndroid,
+    canInstall,
+    install,
+    init
+  };
+};