Family board: tap chores to take, finish or undo them; style number inputs

- Chores on the board are tappable; pick your name (PIN unless a child) and it happens as you
- Up-for-grabs chores offer "I did it" or "Take it for later"
- Number inputs (chore points, time limit) use the dark input style so they are readable
- Tests and README updated

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/sw.js

@@ -1,5 +1,5 @@
 // App-shell cache only; Seafile/API traffic always goes to the network.
-const CACHE = 'hub-v74';
+const CACHE = 'hub-v75';
 const SHARE = 'hub-share'; // files shared into the app from other apps, held until the person picks a folder
 const SHELL = ['/icon.svg', '/manifest.webmanifest', '/icons/icon-192.png', '/icons/apple-touch-icon.png'];