docs: Update Workflows docs - MVP

[BekahHW]

Description

We still have workflows in the docs. This is a quick update just to make things make more sense. I don't want to worry about redirects for the content yet.

AI Code Review

• Team members only: AI review runs automatically when PR is opened or marked ready for review
• Team members can also trigger a review by commenting @continue-review

Checklist

• [] I've read the contributing guide
• [] The relevant docs, if any, have been updated or created
• [] The relevant tests, if any, have been updated or created

Screen recording or screenshot

[ When applicable, please include a short screen recording or screenshot - this makes it much easier for us as contributors to review and understand your changes. See this PR as a good example. ]

Tests

[ What tests were added or updated to ensure the changes work as expected? ]

---

Summary by cubic

Update Mission Control docs to “Cloud Agent Workflows” with simpler setup and monitoring. Adds a separate GitHub Trigger option, clarifies manual vs automatic kickoff, updates links and CTAs to the Agents pages, and notes PR visibility in the Inbox, timeline, and checks.

^{Written for commit c91247b. Summary will update on new commits.}