A .csv file opens as a sortable table in the repository's file view #10726

Intent: a CSV in a repository reads as a table in the browser, as the P12 umbrella asks, without shipping a library.

Done when:

• [ ] The file view renders .csv/.tsv up to 1 MB as an escaped HTML table, server-rendered, first 500 rows, with a "Raw" link beside it; larger files show the raw view as today.
• [ ] Click-to-sort on a header uses under 1 KB of JavaScript, or none (links with ?sort=).
• [ ] Quoted fields, embedded commas and newlines, and cells beginning with = or <script> render as text (a test covers each).
• [ ] A test fails without the renderer; the page stays within the file view's existing time budget.

Files: src/web/pages/ file view, a new small csv module under src/text/, a new test; docs/features/ one short page. Risks: only CSV here; STL and the other kinds are #7335 and siblings.

Done on main already, waiting for you to close it: 6cc5f85f0480915fa524196d3ab7cc81fea3e801 a15363056cde33c93193ded518556fe036d62b6f

Closed: already done on main in 6cc5f85, a153630. Closed by the crew's live triage; reopen it to undo, and it stays open.