Prepare Hub guided self-hosting docs for the next release (#3342)

* docs(hub): drop the manual auth secret from self-hosting setup

Hub generates its authentication secret on first start and stores it in the
database it is already using, so self-hosters no longer run openssl or carry
PASEO_HUB_AUTH_SECRET between restarts. The variable stays as an override for
deployments that must supply the secret from a platform secret store; Hub uses
it without persisting it, so removing it resumes the stored value.

Also corrects a claim that predates this change: rotating the secret does not
invalidate execution credentials already issued. Hub verifies those against
persisted hashes rather than the secret, so only browser sessions end.

Documentation companion to https://github.com/getpaseo/hub/pull/50.

* docs(hub): lead with the local guided setup

* docs(hub): document XDG data directory

* docs: make Hub self-hosting the quickstart

packages/website/src/llms.ts

@@ -60,7 +60,7 @@ ${agents}
 
 - [Changelog](${SITE_URL}/changelog): Release notes for the Paseo daemon, CLI, desktop, and mobile apps.
 - [Download](${SITE_URL}/download): Install Paseo on Mac, Windows, Linux, iOS, Android, or run the web app.
-- [Paseo Hub](${SITE_URL}/hub): Optional service above your daemons that adds GitHub, Slack, and Discord triggers. Self-hosted, private beta.
+- [Paseo Hub](${SITE_URL}/hub): Self-hosted service above your daemons that adds GitHub, Slack, and Discord triggers. A hosted version is planned.
 - [Blog](${SITE_URL}/blog): Updates and technical posts from the Paseo team.
 - [Privacy](${SITE_URL}/privacy): Privacy policy.
 - [GitHub](https://github.com/getpaseo/paseo): Source code, issues, and releases.