The Settings page has grown to 12+ sections spanning over 1200 lines of content. Navigating between sections requires scrolling the entire page, and the back-to-dashboard link scrolls out of view immediately.

Goal: Make the Settings header sticky (with padding reduction on scroll to reclaim space), add a scroll-spy table of contents sidebar on desktop and a dropdown TOC on mobile, and reorganize sections into logical groups (Data Sources, Display, Integrations, Account) for easier scanning.