Faza 3.3: Depozit — Furnizori + Catalog piese + Achiziții

Schema:
- suppliers: name, contact, phone/email/website, pay_terms, delivery_days,
  rating (1-5), discount_pct, categories (JSON), is_active, notes
- parts: name, article (UNIQUE per tenant), brand, category, qty/unit/min_qty,
  buy_price/sell_price, location (rack/bin), barcode, preferred_supplier_id,
  is_active. Index pe (company_id, category) și (company_id, is_active).
- purchases: număr unique per tenant + an, supplier_id, status workflow
  (draft/ordered/received/cancelled), order/expected/received/paid_at, total
- purchase_items: name, article, qty, unit, buy_price, total auto, received bool;
  link opțional la part_id
- wo_parts + part_id: linkare opțională la catalog (alter migration)

Modele cu logică:
- Part::adjustStock($delta) — modifică qty cu validare ≥ 0
- Part::isLow() / isOut() helpers
- Purchase::markReceived() — atomic: marchează items ca received + creste qty
  pe pieces din catalog (DB::transaction)
- WorkOrderPart::updating event — la trecerea status='installed' decrementează
  stoc auto. La revenire (ex: storno) incrementează la loc.
- PurchaseItem::saving — total = qty * buy_price; recalc parent total

Filament resources (group Depozit):
- SupplierResource: form 3 secțiuni, rating ★★★★★, TagsInput pentru categorii
- PartResource: form 4 secțiuni, badge nav cu nr. piese sub stoc minim,
  filtre low_stock + out_of_stock, coloană qty colorată după stoc
- PurchaseResource: form antet + RelationManager Items.
  Action 'Recepționează' care apelează markReceived() — un click = stoc actualizat

WorkOrder PartsRelationManager updated:
- Selector din catalog (Part::active) cu stoc afișat
- Auto-fill name/article/brand/unit/buy_price/sell_price din piesa selectată
- Helper text: la status='installed' se scade din stoc

Widget low-stock:
- TableWidget pe dashboard tenant, listează piesele cu qty <= min_qty
- Span full, sortat după qty (cele mai critice sus)

Seed:
- 2 furnizori (AutoParts Moldova SRL ★5, Inter Cars Moldova ★4)
- 5 piese demo: Ulei Shell, Filtru Mann, Plăcuțe Brembo, Antigel (qty=0!), Bujii NGK
- 1 achiziție recepționată (P-26-0001) cu 2 articole linked la catalog

Total Filament tenant routes: 63 (de la 31).

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

@@ -2,10 +2,12 @@
 
 namespace App\Filament\Tenant\Resources\WorkOrderResource\RelationManagers;
 
+use App\Models\Tenant\Part;
 use App\Models\Tenant\WorkOrderPart;
 use Filament\Actions;
 use Filament\Forms;
 use Filament\Resources\RelationManagers\RelationManager;
+use Filament\Schemas\Components\Utilities\Set;
 use Filament\Schemas\Schema;
 use Filament\Tables;
 use Filament\Tables\Table;
@@ -19,9 +21,28 @@ class PartsRelationManager extends RelationManager
     public function form(Schema $schema): Schema
     {
         return $schema->components([
+            Forms\Components\Select::make('part_id')
+                ->label('Din catalog (lasă gol pentru text liber)')
+                ->options(fn () => Part::where('is_active', true)
+                    ->get()
+                    ->mapWithKeys(fn ($p) => [$p->id => "{$p->name} " . ($p->article ? "[{$p->article}] " : '') . "(stoc: {$p->qty})"])
+                    ->toArray())
+                ->searchable()
+                ->live()
+                ->afterStateUpdated(function ($state, Set $set) {
+                    if ($state && $part = Part::find($state)) {
+                        $set('name', $part->name);
+                        $set('article', $part->article);
+                        $set('brand', $part->brand);
+                        $set('unit', $part->unit);
+                        $set('buy_price', $part->buy_price);
+                        $set('sell_price', $part->sell_price);
+                    }
+                })
+                ->columnSpanFull(),
             Forms\Components\TextInput::make('name')->label('Denumire')->required()->columnSpanFull(),
             Forms\Components\TextInput::make('article')->label('Cod articol')->maxLength(64),
-            Forms\Components\TextInput::make('brand')->label('Brand')->maxLength(64),
+            Forms\Components\TextInput::make('brand')->maxLength(64),
             Forms\Components\TextInput::make('qty')->label('Cantitate')->numeric()->default(1)->required(),
             Forms\Components\TextInput::make('unit')->label('UM')->maxLength(16)->default('buc'),
             Forms\Components\TextInput::make('buy_price')->label('Preț achiziție')->numeric()->default(0),
@@ -30,7 +51,8 @@ class PartsRelationManager extends RelationManager
             Forms\Components\Select::make('status')
                 ->options(WorkOrderPart::STATUSES)
                 ->default('needed')
-                ->required(),
+                ->required()
+                ->helperText('La trecere pe „Montată" se scade automat din stoc.'),
             Forms\Components\Textarea::make('notes')->label('Observații')->columnSpanFull()->rows(2),
         ]);
     }