Add contract management and invoice settings pages

- Created a new Blade view for managing brand contracts with forms for adding and editing contracts, including client and category selection.
- Implemented success message notifications for contract actions.
- Added a new Blade view for invoice settings, allowing customization of invoice number format, header branding, and default values for new invoices.
- Introduced a new PDF view for generating rate cards with customizable styles based on user profile settings.
- Developed a profile management page for rate cards, enabling users to update their identity, appearance, and visibility settings.

app/Models/RateCardProfile.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class RateCardProfile extends Model
+{
+    protected $fillable = [
+        'owner_name', 'tagline', 'whatsapp',
+        'ig_handle', 'tiktok_handle', 'youtube_handle', 'email',
+        'logo_path', 'bg_color', 'accent_color', 'text_color',
+        'custom_footer', 'show_prices', 'access_token',
+    ];
+
+    protected $casts = [
+        'show_prices' => 'boolean',
+    ];
+
+    /** Get the singleton profile, creating defaults if needed */
+    public static function getSingleton(): self
+    {
+        return static::firstOrCreate([], [
+            'owner_name'   => config('app.name', 'KOL Manager'),
+            'bg_color'     => '#FFF8F0',
+            'accent_color' => '#FFB7C5',
+            'text_color'   => '#374151',
+            'show_prices'  => true,
+        ]);
+    }
+
+    public function getWhatsappUrlAttribute(): ?string
+    {
+        if (! $this->whatsapp) return null;
+        $number = preg_replace('/[^0-9]/', '', $this->whatsapp);
+        return "https://wa.me/{$number}";
+    }
+
+    public function getLogoUrlAttribute(): ?string
+    {
+        return $this->logo_path
+            ? route('files.serve-profile-logo')
+            : null;
+    }
+}