Adds Web App Manifest, a minimal Service Worker, and Apple/Android meta
tags so the app can be added to a phone home screen and opens full-screen
in standalone mode (no browser chrome).
- static/manifest.json: name, short_name, display=standalone, icons
- static/sw.js: minimal SW served at /sw.js (root scope) via new Flask route
- static/icon-192.png, icon-512.png: generated by sbin/gen_icons.py (stdlib only)
- base.html: manifest link, theme-color, apple-mobile-web-app-* tags, SW registration
iterminate