feat: establish reservation portal foundation

app/Domain/Reservations/Services/AvailabilityService.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Domain\Reservations\Services;
+
+use App\Domain\Inventory\Models\SnipeAsset;
+use App\Domain\Reservations\Enums\ReservationItemStatus;
+use DateTimeInterface;
+
+class AvailabilityService
+{
+    public function isAvailable(SnipeAsset $asset, DateTimeInterface $startsAt, DateTimeInterface $endsAt): bool
+    {
+        if (! $asset->active || ! $asset->requestable || $asset->assigned_id !== null) {
+            return false;
+        }
+
+        $hasReservationConflict = $asset->reservationItems()
+            ->whereIn('status', ReservationItemStatus::blockingValues())
+            ->where('starts_at', '<', $endsAt)
+            ->where('ends_at', '>', $startsAt)
+            ->exists();
+
+        if ($hasReservationConflict) {
+            return false;
+        }
+
+        return ! $asset->blocks()
+            ->where('starts_at', '<', $endsAt)
+            ->where('ends_at', '>', $startsAt)
+            ->exists();
+    }
+}