fix: validate attributeId > 0 in saveAttributeLink() (#4508)

- Add early validation to reject attributeId <= 0
- Ensure consistent handling of invalid attribute_id in INSERT/UPDATE paths
- Prevent foreign key constraint violations from invalid attribute references

Fixes #4460

Co-authored-by: Ollama <ollama@steganos.dev>
Co-authored-by: objecttothis <17935339+objecttothis@users.noreply.github.com>

app/Models/Attribute.php

@@ -601,6 +601,10 @@ class Attribute extends Model
      */
     public function saveAttributeLink(int $itemId, int $definitionId, int $attributeId): bool
     {
+        if ($attributeId <= 0) {
+            return false;
+        }
+
         $normalizedItemId = empty($itemId) ? null : $itemId;
         $normalizedAttributeId = empty($attributeId) ? null : $attributeId;