add default sorting for incoming letters

app/Filament/Resources/IncomingLetterResource.php

@@ -11,6 +11,7 @@ use Filament\Resources\Resource;
 use Filament\Tables;
 use Filament\Tables\Columns\TextColumn;
 use Filament\Tables\Table;
+use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Support\Carbon;
 
 class IncomingLetterResource extends Resource
@@ -42,7 +43,7 @@ class IncomingLetterResource extends Resource
             ->columns([
                 TextColumn::make('number')
                     ->searchable()
-                    ->sortable(),
+                    ->sortable(query: fn (Builder $query, string $direction) => $query->orderByRaw("CAST(number AS UNSIGNED) $direction")),
 
                 TextColumn::make('name')
                     ->searchable()