fix(auth): unblock the about page for unauthenticated visitors

The /about page (GeoLite2 attribution) was listed in proxy.ts
PUBLIC_PATHS but missed in AuthShell's client-side PUBLIC_PATHS, so
unauthenticated visitors bounced through /auth/login. Add /about to
the AuthShell list and treat it as a standalone public page (same
edge-to-edge render as /privacy).

Apply safe-area-inset-top on the privacy and about sticky headers so
iOS notch / Dynamic Island viewports don't overlap the brand row. Add
a default-closed Contents <details> TOC at the top of the privacy
policy and wrap every HealthKit identifier <code> with break-all so
long camelCase strings (heartRateVariabilitySDNN,
environmentalAudioExposure) wrap inside narrow viewports.

src/app/about/page.tsx

@@ -56,7 +56,7 @@ function Section({
 export default function AboutPage() {
   return (
     <div className="bg-background text-foreground min-h-dvh">
-      <header className="border-border/60 bg-background/80 sticky top-0 z-10 border-b backdrop-blur">
+      <header className="border-border/60 bg-background/80 sticky top-0 z-10 border-b backdrop-blur pt-[env(safe-area-inset-top)]">
         <div className="mx-auto flex max-w-3xl items-center justify-between px-4 py-3 md:px-6">
           <Link
             href="/"