feat: add support for multiple event dates in variants

- Updated the FeaturedGroupService to include 'variants.eventDates' in the items query.
- Introduced a BelongsToMany relationship in EventDate for selected variants.
- Modified PurchaseItemResource and PurchaseItemSnapshotFactory to handle multiple event dates for variants.
- Enhanced StartCheckoutService to load event dates for variants.
- Updated TicketGeneratorService to accommodate event dates in ticket generation.
- Created migrations to support multi-value event dates and allow multiple variant values per attribute.
- Adjusted seeders to reflect new event date handling and added new attributes.
- Added tests to ensure correct functionality for multi-date variants and their integration with ticket generation.

app/Domains/Event/Models/EventDate.php

@@ -9,6 +9,7 @@ use Illuminate\Database\Eloquent\Attributes\Fillable;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Support\Carbon;
 
@@ -43,6 +44,17 @@ class EventDate extends Model
         return $this->hasMany(Variant::class);
     }
 
+    /** @return BelongsToMany<Variant, $this> */
+    public function selectedByVariants(): BelongsToMany
+    {
+        return $this->belongsToMany(
+            Variant::class,
+            'variant_event_dates',
+            'event_date_id',
+            'variant_id',
+        );
+    }
+
     public function startsAt(): CarbonInterface
     {
         return Carbon::parse($this->date->format('Y-m-d').' '.$this->time_start);