Shared performance pages load reliably

Opening a shared performance link should feel instant again, even when the underlying account has a large trade history. Pages that used to fail with a database timeout now load normally, and view counts still increment in the background.

Link previews also work when you paste a shared URL into Slack, iMessage, or social apps. The Open Graph image for shared pages no longer breaks, so recipients see a proper preview card instead of a blank or generic thumbnail.