fix: wrap bare intersection types in parentheses when adding nullable (#1756)

When a MorphTo relation's docblock uses a bare intersection type in the
generic parameter (e.g. `MorphTo<BaseModel&CanBeAssigned, $this>`), the
generated property type incorrectly becomes `BaseModel&CanBeAssigned|null`
instead of the correct `(BaseModel&CanBeAssigned)|null`.

This adds `wrapIntersectionType()` which ensures bare intersection types
are wrapped in parentheses before `|null` is appended, producing valid
DNF type syntax. Applied in both `setProperty()` and `applyNullability()`.

src/Console/ModelsCommand.php

@@ -534,7 +534,7 @@ class ModelsCommand extends Command
         }
 
         if ($isNullable) {
-            $type .= '|null';
+            $type = $this->wrapIntersectionType($type) . '|null';
         } else {
             $type = str_replace($nullString, '', $type);
         }
@@ -542,6 +542,22 @@ class ModelsCommand extends Command
         return $type;
     }
 
+    /**
+     * Wraps a bare intersection type in parentheses for correct DNF syntax.
+     *
+     * For example, `A&B` becomes `(A&B)` so that adding `|null` produces
+     * `(A&B)|null` instead of the ambiguous `A&B|null`.
+     * Types that are already parenthesized or contain union types are returned as-is.
+     */
+    protected function wrapIntersectionType(string $type): string
+    {
+        if (str_contains($type, '&') && !str_contains($type, '|') && $type[0] !== '(') {
+            return '(' . $type . ')';
+        }
+
+        return $type;
+    }
+
     /**
      * Returns the override type for the give type.
      *
@@ -995,7 +1011,7 @@ class ModelsCommand extends Command
         if ($type !== null) {
             $newType = $this->getTypeOverride($type);
             if ($nullable) {
-                $newType .= '|null';
+                $newType = $this->wrapIntersectionType($newType) . '|null';
             }
             $this->properties[$name]['type'] = $newType;
         }