web: official ensō+key icon, Kaizenkodo link, installable home-screen app

- App icon = the official Kaizenkodo ensō (logo/current/exports/tight) with a key
  inside: cream bg for the home-screen/app icon, transparent for the header +
  favicons. Source: assets/enso-base.png + icon-source.svg / enso-mark.svg.
- Attribution: a 'by Kaizenkodo' header link and a footer line, both to kaizenkodo.no.
- PWA install: manifest (standalone, start_url/scope '../', maskable icons) + iOS
  metas (apple-mobile-web-app-capable/title/status-bar) so it adds to the iPhone
  home screen and runs as a standalone app.

helwasm/style.css

@@ -66,6 +66,8 @@ body {
 .wordmark { font-family: var(--disp); font-weight: 700; font-size: 22px; color: var(--ocean); letter-spacing: -0.01em; }
 .tagline { font-family: var(--mono); font-size: 11px; color: var(--muted); letter-spacing: 0.08em; }
 .nav-spacer { flex: 1; }
+.byline { font-family: var(--mono); font-size: 11px; color: var(--muted); text-decoration: none; letter-spacing: 0.04em; border-bottom: 1px solid transparent; margin-left: 6px; align-self: center; }
+.byline:hover { color: var(--ocean); border-bottom-color: currentColor; }
 
 /* Eyebrow label */
 .eyebrow {
@@ -249,11 +251,13 @@ input.mask { -webkit-text-security: disc; }
 .modal .row { display: flex; gap: 10px; margin-top: 14px; }
 
 .foot { color: var(--muted); font-family: var(--mono); font-size: 12px; text-align: center; padding: 8px 0 40px; }
+.foot a { color: var(--ocean); text-decoration: none; border-bottom: 1px solid rgba(27, 65, 97, 0.3); }
+.foot a:hover { border-bottom-color: var(--ocean); }
 
 @media (max-width: 680px) {
   .fields { grid-template-columns: 1fr; align-items: stretch; }
   .nav { gap: 9px; height: 60px; }
-  .tagline { display: none; }
+  .tagline, .byline { display: none; }
   body { font-size: 15px; }
   /* result row stacks cleanly on phones: the password on its own full-width line,
      then a tidy meta line (result + len ........ Copy / Store). */