feat: Add notification services for Email, Telegram, and WhatsApp

- Implement EmailNotifier for sending batch and test notifications via email.
- Implement TelegramNotifier for sending batch and test notifications via Telegram.
- Implement WahaNotifier for sending batch and test notifications via WhatsApp using WAHA API.
- Create migration for client_categories table and update clients table to include category_id.
- Create migration for notification_settings table to manage notification configurations.
- Add ClientCategorySeeder to populate default client categories.
- Create manifest.json for PWA support.
- Implement service worker (sw.js) for caching static assets and offline support.
- Add edit event view for modifying scheduled events.
- Create search results view for displaying search queries.
- Develop notification settings view for configuring notification channels and triggers.

public/sw.js

@@ -0,0 +1,61 @@
+// KOL Manager Service Worker
+// Provides basic offline support and caches static assets
+
+const CACHE_NAME = 'kol-manager-v1';
+const STATIC_ASSETS = [
+    '/',
+    '/manifest.json',
+];
+
+// Install — pre-cache shell
+self.addEventListener('install', event => {
+    event.waitUntil(
+        caches.open(CACHE_NAME).then(cache => cache.addAll(STATIC_ASSETS))
+    );
+    self.skipWaiting();
+});
+
+// Activate — clean up old caches
+self.addEventListener('activate', event => {
+    event.waitUntil(
+        caches.keys().then(keys =>
+            Promise.all(keys.filter(k => k !== CACHE_NAME).map(k => caches.delete(k)))
+        )
+    );
+    self.clients.claim();
+});
+
+// Fetch — network-first for HTML/API, cache-first for static assets
+self.addEventListener('fetch', event => {
+    const { request } = event;
+    const url = new URL(request.url);
+
+    // Skip non-GET and cross-origin requests
+    if (request.method !== 'GET' || url.origin !== location.origin) return;
+
+    // Cache-first for Vite build assets (hashed filenames)
+    if (url.pathname.startsWith('/build/')) {
+        event.respondWith(
+            caches.match(request).then(cached => cached || fetch(request).then(response => {
+                const clone = response.clone();
+                caches.open(CACHE_NAME).then(cache => cache.put(request, clone));
+                return response;
+            }))
+        );
+        return;
+    }
+
+    // Network-first for everything else (app routes)
+    event.respondWith(
+        fetch(request)
+            .then(response => {
+                // Cache successful HTML responses
+                if (response.ok && request.headers.get('Accept')?.includes('text/html')) {
+                    const clone = response.clone();
+                    caches.open(CACHE_NAME).then(cache => cache.put(request, clone));
+                }
+                return response;
+            })
+            .catch(() => caches.match(request))
+    );
+});