feat: add in() and notIn() helpers for value membership checking

Author: kettasoft

docs/api/payload.md

@@ -105,6 +105,44 @@ if ($payload->isNull()) {
 
 ---
 
+### `in(...$haystack): bool`
+
+Check if the payload value exists inside the given list.
+Supports both a flat list of values or a single array.
+
+```php
+if ($payload->in('active', 'pending', 'archived')) {
+    // apply filter
+}
+```
+
+---
+
+### `notIn(...$haystack): bool`
+
+Check if the payload value does _not_ exist in the given list.
+
+```php
+if ($payload->notIn('banned', 'deleted')) {
+    // only include safe records
+}
+```
+
+---
+
+### `isBoolean(): bool`
+
+Check if the value can be interpreted as boolean.  
+Supports `"true"`, `"false"`, `"1"`, `"0"`, `"yes"`, `"no"`.
+
+```php
+if ($payload->isBoolean()) {
+    $this->builder->where('is_active', $payload->asBoolean());
+}
+```
+
+---
+
 ### `isJson(): bool`
 
 Check if the payload is a valid JSON string.

src/Support/Payload.php

@@ -216,6 +216,32 @@ public function asBoolean(): ?bool
     return $this->isBoolean() ? filter_var($this->value, FILTER_VALIDATE_BOOLEAN) : null;
   }
 
+  /**
+   * Check if the payload value is in the given haystack.
+   *
+   * @param mixed ...$haystack
+   * @return bool
+   */
+  public function in(...$haystack): bool
+  {
+    if (count($haystack) === 1 && is_array($haystack[0])) {
+      $haystack = $haystack[0];
+    }
+
+    return in_array($this->value, (array) $haystack, true);
+  }
+
+  /**
+   * Check if the payload value is not in the given haystack.
+   *
+   * @param mixed ...$haystack
+   * @return bool
+   */
+  public function notIn(...$haystack): bool
+  {
+    return !$this->in(...$haystack);
+  }
+
   /**
    * Return a new Payload instance with the given value.
    *