new: send stock alert email when offer stock crosses threshold

When a purchase causes an offer's ``stock_current`` to drop to or below
its ``minimum_ondemand`` threshold, an email is sent to
``commande@jardinenvie.com`` using an editable mail template (Spatie
``MailTemplate``).

The check runs in ``OfferStocks::decreaseStock()`` after updating stock.
Only threshold-crossing events trigger the alert (not every low-stock
sale).  Failures are caught and logged to avoid disrupting the order
flow.

app/Mail/AlerteStock.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Mail;
+
+use App\Models\Core\Mail\MailTemplate;
+use Illuminate\Bus\Queueable;
+use Illuminate\Mail\Mailables\Address;
+use Illuminate\Mail\Mailables\Envelope;
+use Illuminate\Queue\SerializesModels;
+use Spatie\MailTemplates\TemplateMailable;
+
+class AlerteStock extends TemplateMailable
+{
+    use Queueable, SerializesModels;
+
+    public $subject;
+
+    public $article;
+
+    public $offre;
+
+    public $stock_restant;
+
+    public $seuil;
+
+    protected static $templateModelClass = MailTemplate::class;
+
+    public function __construct($offer)
+    {
+        $this->article = $offer->article->title ?? 'Article #'.$offer->article_id;
+        $this->offre = $offer->id;
+        $this->stock_restant = $offer->stock_current;
+        $this->seuil = $offer->minimum_ondemand;
+    }
+
+    public function envelope()
+    {
+        return new Envelope(
+            from: new Address('boutique@jardinenvie.com', 'Jardin\'en\'Vie'),
+            subject: $this->subject,
+        );
+    }
+}

app/Repositories/Shop/OfferStocks.php

@@ -2,19 +2,62 @@
 
 namespace App\Repositories\Shop;
 
+use App\Mail\AlerteStock;
 use App\Models\Shop\Offer;
+use Illuminate\Support\Facades\Log;
+use Illuminate\Support\Facades\Mail;
 
 class OfferStocks
 {
     public static function decreaseStock($item)
     {
         $offer = Offers::get($item['offer_id']);
+        $previousStock = $offer->stock_current;
         $offer->stock_current = $offer->stock_current - $item['quantity'];
         if ($offer->stock_current <= 0) {
             $offer->stock_current = 0;
         }
 
-        return $offer->save();
+        $saved = $offer->save();
+
+        if ($saved) {
+            self::checkStockAlert($offer, $previousStock);
+        }
+
+        return $saved;
+    }
+
+    public static function checkStockAlert($offer, $previousStock)
+    {
+        $threshold = (float) $offer->minimum_ondemand;
+        if ($threshold <= 0) {
+            return;
+        }
+
+        $crossedThreshold = $previousStock > $threshold
+            && $offer->stock_current <= $threshold;
+
+        if (! $crossedThreshold) {
+            return;
+        }
+
+        try {
+            $offer->load('article');
+            Mail::to('commande@jardinenvie.com')
+                ->send(new AlerteStock($offer));
+            Log::info('Stock alert email sent', [
+                'offer_id' => $offer->id,
+                'article' => $offer->article->name ?? $offer->article_id,
+                'stock_current' => $offer->stock_current,
+                'threshold' => $threshold,
+            ]);
+        } catch (\Throwable $e) {
+            Log::error('Failed to send stock alert email', [
+                'offer_id' => $offer->id,
+                'stock_current' => $offer->stock_current,
+                'exception' => $e->getMessage(),
+            ]);
+        }
     }
 
     public static function getStockCurrent($id)