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/InvoiceItem.php

@@ -9,11 +9,12 @@ use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
 class InvoiceItem extends Model
 {
-    protected $fillable = ['invoice_id', 'description', 'quantity', 'unit_price', 'total'];
+    protected $fillable = ['invoice_id', 'description', 'quantity', 'unit_price', 'total', 'is_taxable'];
 
     protected $casts = [
         'unit_price' => 'decimal:2',
         'total'      => 'decimal:2',
+        'is_taxable' => 'boolean',
     ];
 
     public function invoice(): BelongsTo