docs(about): document the deliberate no-TOC call for the short-form page

The R4 design review flagged /about as missing the TOC the /privacy
page carries. /about is two sections (Project + Credits) and fits the
fold on every viewport, so a collapsible TOC costs a tap to expand
for negligible payoff. Pin the decision in the file header so a
future reader does not re-open the question on a future polish
sweep.

src/app/about/page.tsx

@@ -18,6 +18,14 @@ import Link from "next/link";
  *
  * The page mirrors `/privacy` in layout and is reachable without a
  * session — see `src/proxy.ts` PUBLIC_PATHS.
+ *
+ * Intentional: no TOC. The `/privacy` page carries a collapsible
+ * `<details>` table of contents because it has eleven numbered
+ * sections that benefit from skim navigation. `/about` is short-form
+ * (Project + Credits) and fits the fold on every viewport we ship to,
+ * so a TOC would cost a tap to expand for negligible payoff. The
+ * scroll-mt-28 anchors stay so deep-links into `#project` /
+ * `#credits` still clear the sticky header on iPhones with a notch.
  */
 
 export const dynamic = "force-static";