PDF: remove part codes; payments: pre-fill amount with balance due

- PDF parts table: removed Cod/article column, widened Denumire column,
  fixed colspan in tfoot from 4 to 3
- PaymentsRelationManager: amount field now defaults to (total - paidAmount)
  so it pre-fills with the remaining balance; always editable

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Filament/Tenant/Resources/WorkOrderResource/RelationManagers/PaymentsRelationManager.php

@@ -25,7 +25,14 @@ class PaymentsRelationManager extends RelationManager
     {
         return $schema->components([
             Forms\Components\DatePicker::make('paid_at')->label(__('Data'))->default(today())->required(),
-            Forms\Components\TextInput::make('amount')->label(__('Sumă'))->numeric()->required(),
+            Forms\Components\TextInput::make('amount')
+                ->label(__('Sumă'))
+                ->numeric()
+                ->required()
+                ->default(function (RelationManager $livewire): float {
+                    $wo = $livewire->getOwnerRecord();
+                    return max(0.0, (float) $wo->total - $wo->paidAmount());
+                }),
             Forms\Components\Select::make('method')
                 ->options(\App\Support\I18n::opts(Payment::METHODS))
                 ->default('cash')