Stage 6 — Purchase System: partial receipt + supplier analytics

Schema:
- purchase_items.qty_received (backfilled from `received` boolean)
- purchases.warehouse_id (target warehouse FK)
- supplier_part_prices (price history per supplier/part with purchase ref)
- New status `partial` between ordered and received

Purchase ↔ Warehouse integration:
- Purchase::receiveItem(item, qty, warehouse?) — routes through
  WarehouseService::receive: creates batch + receipt event + supplier price row
- Purchase::receiveAllRemaining(warehouse?) — receives all outstanding lines
- Purchase::recomputeStatus() — auto: ordered → partial → received

Old flat markReceived() removed — every receipt now writes batches + ledger.

Filament:
- Purchase list: progress %, partial badge, warehouse picker on form
- ItemsRelationManager: per-line "Recepționează" with qty + warehouse modal,
  qty_received shown as "X.XX / Y.YY" with colour
- PartResource: new PriceHistoryRelationManager (supplier price history)
- SupplierResource: derived columns onTimeRate / avgDeliveryDays / spend(90d)
  + "Rerating" action

Analytics:
- App\Services\Warehouse\SupplierAnalytics (onTimeRate, avgDeliveryDays,
  spend, count, computedRating)
- `suppliers:rate` artisan command + weekly schedule (Mon 04:00)
- Computed rating: 70% on-time + 20% volume + 10% speed bonus

Tests (6 new, all pass):
- Partial receipt of 3/10 → status=partial + 1 batch + 1 price row
- receiveAllRemaining → status=received with received_at set
- Over-receive throws InvalidArgumentException
- Two partial receipts (4+6) → 2 batches FIFO + status=received
- onTimeRate 50% with 1 on-time + 1 late
- computedRating null when <2 deliveries

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/Models/Tenant/PurchaseItem.php

@@ -12,16 +12,27 @@ class PurchaseItem extends Model
 
     protected $fillable = [
         'company_id', 'purchase_id', 'part_id',
-        'name', 'article', 'qty', 'unit', 'buy_price', 'total', 'received',
+        'name', 'article', 'qty', 'qty_received', 'unit', 'buy_price', 'total', 'received',
     ];
 
     protected $casts = [
         'qty' => 'decimal:2',
+        'qty_received' => 'decimal:2',
         'buy_price' => 'decimal:2',
         'total' => 'decimal:2',
         'received' => 'boolean',
     ];
 
+    public function isFullyReceived(): bool
+    {
+        return (float) $this->qty_received + 0.001 >= (float) $this->qty;
+    }
+
+    public function outstanding(): float
+    {
+        return max(0.0, (float) $this->qty - (float) $this->qty_received);
+    }
+
     public function purchase(): BelongsTo
     {
         return $this->belongsTo(Purchase::class);