Use a persistent Browserbase browser context (contextId) to keep state across sessions

Documented steps

1. Create a persistent browser context in the dashboard/API once; it stores state such as cookies, localStorage, and extensions in an isolated context.
2. Capture the contextId returned when the context is created.
3. At session creation, pass that contextId (e.g. `bb.sessions.create({ contextId: "..." })`) so the new session loads the saved profile/state.
4. Reuse the same contextId across multiple sessions to persist logins and preferences without re-authenticating.
5. Official doc: https://docs.browserbase.com/platform/browser/core-features/contexts