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/board.html

@@ -65,6 +65,8 @@
   #ov { position: fixed; inset: 0; background: rgba(0,0,0,.6); display: grid; place-items: center; padding: 18px; } #ov[hidden] { display: none; }
   #ovb { background: var(--panel); border: 1px solid var(--line); border-radius: 20px; padding: 20px; width: 100%; max-width: 380px; text-align: center; }
   .err { color: var(--danger); min-height: 20px; }
+  .pbtn { width: 34px; height: 34px; border-radius: 50%; background: var(--accent); color: var(--accent-t, #fff); border: 0; font-size: 24px; line-height: 1; cursor: pointer; flex: none; }
+  #ovb input[type=text], #ovb input[type=date], #ovb input[type=time], #ovb select { width: 100%; min-height: 48px; padding: 0 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--panel2); color: var(--text); font-size: 17px; }
   .pill { display: inline-flex; align-items: center; gap: 6px; margin: 3px 6px 3px 0; padding: 6px 12px; border-radius: 16px; background: var(--panel2); border: 1px solid var(--line); color: var(--text); font: inherit; font-size: 15px; cursor: pointer; } .pill.pool { border-color: var(--accent); } .pill small { color: var(--muted); font-size: 12px; } .pill.more { background: none; border-style: dashed; color: var(--muted); cursor: default; }
   .chp { margin-top: 8px; } .chp .top { display: flex; justify-content: space-between; align-items: baseline; }
   /* a tablet (like a 12.9-inch iPad) shows the whole board at once, with no scrolling */