feat: Part product images + seasonal tire-swap reminders

Part (HasMedia):
- Spatie media `image` single-file collection + imageUrl() helper
- PartResource form: image upload section (image editor, 2 MB max)
- Parts list: circular thumbnail column
- Shop catalog cards: square thumbnail + 📦 placeholder
- Shop part detail: 260px image alongside info, single column when no image

Seasonal tire-swap reminders:
- NotificationDispatcher::tireSeasonalSwap(TireSet) — Telegram first, email
  fallback (when set has a vehicle, via ServiceReminderMail with 'tire_swap'
  type and a size-aware note)
- tires:remind-seasonal artisan command, self-gating to Feb 15-Mar 15
  (notify winter sets stored) and Sep 15-Oct 15 (notify summer sets stored).
  60-day cooldown per client via service_reminders_sent. --force / --dry-run.
- Schedule: weekly Mon 09:30

Tests (6 new):
- outside window no-ops; spring window notifies winter; spring ignores summer;
  autumn notifies summer; cooldown blocks doubles; --force overrides window

Full suite: 106 passed.

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

app/Models/Tenant/Part.php

@@ -7,10 +7,25 @@ use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Database\Eloquent\SoftDeletes;
+use Spatie\MediaLibrary\HasMedia;
+use Spatie\MediaLibrary\InteractsWithMedia;
 
-class Part extends Model
+class Part extends Model implements HasMedia
 {
-    use BelongsToTenant, SoftDeletes;
+    use BelongsToTenant, InteractsWithMedia, SoftDeletes;
+
+    public function registerMediaCollections(): void
+    {
+        $this->addMediaCollection('image')->singleFile();
+    }
+
+    public function imageUrl(): ?string
+    {
+        $m = $this->getFirstMedia('image');
+        if (! $m) return null;
+        if (! @file_exists($m->getPath())) return null;
+        return $m->getUrl();
+    }
 
     public const CATEGORIES = [
         'Ulei', 'Filtre', 'Frâne', 'Suspensie', 'Lichide',