Family board: add to shopping, tasks, checklists and the Family calendar; record who added each

- + button on each board card: write it, tap your name (PIN unless a child), it is added as you
- Tasks, events, checklist items and shopping items remember who added them
- Names shown on the board and in Tasks, Notes and Calendar
- 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-v77';
+const CACHE = 'hub-v78';
 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'];