docs: link profile sync from quickstarts

[MagMueller]

What changed

The V4 agent and browser quickstarts now link the existing profile-sync guide at the point where users need persistent cookies and local storage.

• Agent runs name browserSettings.profileId.
• Browser sessions name profileId.
• The generated full documentation files are refreshed.

Why

A 2027 profile-persistence run needed 12 documentation fetches before finding the existing guide. The guide was already correct; the two main V4 entry points could not point to it.

Checks

• Generated the LLM files twice; the result was idempotent.
• Parsed docs/docs.json and verified /cloud/guides/profile-sync exists.
• Mintlify broken-links passed with no findings.
• git diff --check passed.

This is documentation only. It does not change SDK or API behavior.

---

Summary by cubic

Links the existing profile-sync guide from the V4 agent and browser quickstarts so users can find how to keep cookies and local storage between runs. The quickstarts now point to /cloud/guides/profile-sync and show passing the profile ID as browserSettings.profileId for agents and profileId for browsers. Also regenerates the full documentation text files.

^{Written for commit f59bc9f. Summary will update on new commits.}