fix: add credentials:'include' to regen fetch so HF cookies are sent

ZeroGPU quota is attributed via the HF session cookie. Without
credentials:'include', the fetch to /gradio_api/queue/join omits
cookies because the Space origin (*.hf.space) differs from the HF
auth origin (huggingface.co), causing all regen calls to be treated
as unauthenticated (2min quota) even for PRO users.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -2093,6 +2093,7 @@ _GLOBAL_JS = """
 
     fetch('/gradio_api/queue/join', {
       method: 'POST',
+      credentials: 'include',
       headers: {'Content-Type': 'application/json'},
       body: JSON.stringify({
         data: data,