fix: skip all API calls when generateGuestId is false and no userId is provided

[christianmat]

Summary

When generateGuestId is set to false and no userId is provided, the SDK previously still sent a POST /v1/public/flowStates request with an auto-generated guest ID on initialization, page navigation, and tab focus. This contradicted the prop's documented behavior ("Frigade will not initialize or render any Flows until a userId is provided") and generated API traffic for anonymous visitors.

• Added a guard in Fetchable.fetch() that skips all API requests when generateGuestId === false and the effective userId is missing or a guest_ ID. Since every request (flowStates, sessions, flow responses, tracking) goes through this method, this covers the full surface.
• The flowStates refresh closure also returns early in this mode so the skipped request isn't misreported by hasFailedToLoad().
• Global state is still initialized, so isReady() remains true and calling identify() with a real userId resumes normal behavior.

Test plan

• Existing integration test can disable guest id generation passes (no flows anonymously → identify() → flows load)
• Verified with a mocked fetch that zero requests occur with generateGuestId: false and no userId, and that requests resume after identify()
• Typecheck passes

Made with Cursor