fix(PageRequest): Set default mode to LIVE and update related tests

- Changed default mode in PageRequest from null to LIVE.
- Updated tests to reflect the new default mode and ensure correct behavior.

Author: fmontes

src/Request/PageRequest.php

@@ -49,7 +49,7 @@ class PageRequest
     /**
      * @var string|null The mode (LIVE, WORKING, EDIT_MODE)
      */
-    private ?string $mode = null;
+    private ?string $mode = self::MODE_LIVE;
 
     /**
      * @var string|null The host ID (Site ID)

tests/Request/PageRequestTest.php

@@ -85,7 +85,7 @@ public function testWithModeReturnsNewInstance(): void
         $request2 = $request1->withMode('PREVIEW_MODE');
 
         $this->assertNotSame($request1, $request2);
-        $this->assertNull($request1->getMode());
+        $this->assertEquals('LIVE', $request1->getMode());
         $this->assertEquals('PREVIEW_MODE', $request2->getMode());
     }
 
@@ -236,7 +236,7 @@ public function testBuildQueryParamsReturnsEmptyArrayWhenNoParamsSet(): void
     {
         $request = new PageRequest('/test');
 
-        $this->assertEquals([], $request->buildQueryParams());
+        $this->assertEquals(['mode' => 'LIVE'], $request->buildQueryParams());
     }
 
     /**