Lightpanda: fetch() and XMLHttpRequest attach session cookies to cross-origin requests regardless of credentials mode

Lightpanda is a headless browser designed for AI and automation. Prior to 0.2.9, Lightpanda fetch() and XMLHttpRequest unconditionally attached session cookies to every HTTP request, ignoring credentials: omit, credentials: same-origin, credentials: include, and XMLHttpRequest.withCredentials, allowing an attacker-controlled origin in a Lightpanda session to issue authenticated cross-origin requests against a victim origin. This issue is fixed in version 0.2.9.