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/assets/site.webmanifest

@@ -1,11 +1,15 @@
 {
   "name": "LesS/KEY — password generator",
   "short_name": "LesS/KEY",
-  "icons": [
-    { "src": "./icon-192.png", "sizes": "192x192", "type": "image/png" },
-    { "src": "./icon-512.png", "sizes": "512x512", "type": "image/png" }
-  ],
+  "description": "A password manager that stores nothing and runs entirely in your browser. A free tool by Kaizenkodo.",
+  "id": "../",
+  "start_url": "../",
+  "scope": "../",
+  "display": "standalone",
   "theme_color": "#0a2540",
   "background_color": "#f4f0e8",
-  "display": "standalone"
+  "icons": [
+    { "src": "./icon-192.png", "sizes": "192x192", "type": "image/png", "purpose": "any maskable" },
+    { "src": "./icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "any maskable" }
+  ]
 }