(fix): restore Document tenant int cast, validate relationship $id, fix PHPStan types

- Restore numeric-to-int cast in Document::getTenant() that was removed
  in 89e7afc. MongoDB is type-strict: stored int 999 won't match query
  string "999". The cast ensures tenant values stay as ints after the
  ColumnType::Id string cast in castingAfter.
- Add validation for null $id on relationship Document values during
  update, throwing RelationshipException instead of auto-creating.
- Fix PHPStan annotations: use inline @phpstan-ignore for Document
  constructor calls, update MongoTenantFilter closure return type.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: abnegate

src/Database/Document.php

@@ -241,7 +241,13 @@ public function getUpdatedAt(): ?string
      */
     public function getTenant(): int|string|null
     {
-        return $this->getAttribute('$tenant');
+        $tenant = $this->getAttribute('$tenant');
+
+        if (\is_numeric($tenant)) {
+            return (int) $tenant;
+        }
+
+        return $tenant;
     }
 
     /**

src/Database/Hook/MongoTenantFilter.php

@@ -17,7 +17,7 @@ class MongoTenantFilter implements Read
     /**
      * @param int|string|null $tenant The current tenant ID
      * @param bool $sharedTables Whether shared tables mode is enabled
-     * @param Closure(string, array<int|string>=): (int|string|null|array<string, array<int|string>>) $getTenantFilters Closure that returns tenant filter values for a collection
+     * @param Closure(string, array<int|string>=): (int|string|null|array<string, array<int|string|null>>) $getTenantFilters Closure that returns tenant filter values for a collection
      */
     public function __construct(
         private int|string|null $tenant,

src/Database/Hook/Relationships.php

@@ -148,8 +148,7 @@ public function afterDocumentCreate(Document $collection, Document $document): D
 
             try {
                 if (\is_array($value) && ! \array_is_list($value)) {
-                    /** @var array<string, mixed> $value */
-                    $value = new Document($value);
+                    $value = new Document($value); // @phpstan-ignore argument.type
                     $document->setAttribute($key, $value);
                 }
 
@@ -287,8 +286,7 @@ public function afterDocumentUpdate(Document $collection, Document $old, Documen
             $value = $document->getAttribute($key);
 
             if (\is_array($value) && ! \array_is_list($value)) {
-                /** @var array<string, mixed> $value */
-                $value = new Document($value);
+                $value = new Document($value); // @phpstan-ignore argument.type
                 $document->setAttribute($key, $value);
             }
 
@@ -536,6 +534,10 @@ public function afterDocumentUpdate(Document $collection, Document $old, Documen
                             }
                             $this->db->purgeCachedDocument($relatedCollection->getId(), $value);
                         } elseif ($value instanceof Document) {
+                            if (empty($value->getId())) {
+                                throw new RelationshipException('Invalid relationship value. Document must have a valid $id.');
+                            }
+
                             $related = $this->db->skipRelationships(
                                 fn () => $this->db->getDocument($relatedCollection->getId(), $value->getId(), [Query::select(['$id'])])
                             );