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/Filament/Tenant/Resources/PartResource/RelationManagers/PriceHistoryRelationManager.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Filament\Tenant\Resources\PartResource\RelationManagers;
+
+use Filament\Resources\RelationManagers\RelationManager;
+use Filament\Tables;
+use Filament\Tables\Table;
+
+class PriceHistoryRelationManager extends RelationManager
+{
+    protected static string $relationship = 'priceHistory';
+
+    protected static ?string $title = 'Istoric prețuri furnizori';
+
+    public function table(Table $table): Table
+    {
+        return $table
+            ->columns([
+                Tables\Columns\TextColumn::make('observed_at')
+                    ->label('Data')
+                    ->dateTime('d.m.Y H:i')
+                    ->sortable(),
+                Tables\Columns\TextColumn::make('supplier.name')->label('Furnizor')->searchable(),
+                Tables\Columns\TextColumn::make('purchase.number')->label('PO')->placeholder('—'),
+                Tables\Columns\TextColumn::make('price')
+                    ->money('MDL')
+                    ->alignRight()
+                    ->sortable(),
+                Tables\Columns\TextColumn::make('currency')->label('Val.'),
+            ])
+            ->defaultSort('observed_at', 'desc')
+            ->emptyStateHeading('Niciun preț înregistrat')
+            ->emptyStateDescription('Prețurile se înregistrează automat la fiecare recepție de PO.');
+    }
+}