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.

app/Models/NotificationSetting.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class NotificationSetting extends Model
+{
+    protected $fillable = [
+        'name', 'channel', 'config', 'triggers',
+        'is_enabled', 'notify_before_hours',
+    ];
+
+    protected $casts = [
+        'config'               => 'array',
+        'triggers'             => 'array',
+        'is_enabled'           => 'boolean',
+        'notify_before_hours'  => 'integer',
+    ];
+
+    // ── Channel icons/labels ─────────────────────────────────────
+
+    public static array $channelMeta = [
+        'email'     => ['icon' => '✉️',  'label' => 'Email',     'color' => '#AEC6CF'],
+        'telegram'  => ['icon' => '✈️',  'label' => 'Telegram',  'color' => '#E8D5F5'],
+        'whatsapp'  => ['icon' => '💬',  'label' => 'WhatsApp',  'color' => '#B5EAD7'],
+    ];
+
+    public function getChannelIconAttribute(): string
+    {
+        return static::$channelMeta[$this->channel]['icon'] ?? '🔔';
+    }
+
+    public function getChannelLabelAttribute(): string
+    {
+        return static::$channelMeta[$this->channel]['label'] ?? ucfirst($this->channel);
+    }
+
+    // ── Trigger helpers ──────────────────────────────────────────
+
+    public static array $triggerMeta = [
+        'upcoming_event' => ['icon' => '📅', 'label' => 'Upcoming Events'],
+        'invoice_due'    => ['icon' => '🧾', 'label' => 'Invoice Due Date'],
+        'content_due'    => ['icon' => '🎬', 'label' => 'Content Target Date'],
+    ];
+
+    public function hasTrigger(string $trigger): bool
+    {
+        return in_array($trigger, $this->triggers ?? []);
+    }
+}