Parent controls for children, name-tile sign-in, restricted Learn search, simple mode

- Sign-in page shows name tiles on remembered devices; tap a name, then PIN or passkey
- Music and Movies are separate on the server; Plex can be locked to a child's managed profile
- Activity log, weekly summary and alerts to parents; per-area and weekend limits
- Requests from children (Ask button) answered in Settings; bonus screen time from rewards
- Restricted Learn search (Simple English Wikipedia, blocked words) replaces web search for children
- Simple mode (big-button home) for young children or grandparents
- Child usage kept in memory instead of read from disk on every request
- Tests and README updated

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

public/style.css

@@ -1063,3 +1063,14 @@ body.vizopen { overflow: hidden; }
 
 .crtick { position: absolute; top: 0; width: 2px; height: 100%; background: var(--text); opacity: .55; } .crearn { display: flex; align-items: center; gap: 10px; margin: 6px 0 0 52px; padding: 8px 10px; border-radius: 12px; background: var(--panel2); } .crearn .btn { min-height: 34px; padding: 0 12px; }
 .crdet { margin: 6px 0 0 52px; } .crdet summary { cursor: pointer; color: var(--muted); font-size: 14px; } .crwk { padding: 8px 0; border-bottom: 1px solid var(--line); } .crwk:last-child { border-bottom: 0; }
+
+#kidreq { position: fixed; left: 12px; bottom: calc(env(safe-area-inset-bottom, 0px) + 74px); z-index: 55; min-height: 40px; padding: 0 16px; border-radius: 22px; border: 1px solid var(--line); background: var(--panel); color: var(--text); font: inherit; font-weight: 600; box-shadow: 0 4px 14px rgba(0,0,0,.3); cursor: pointer; }
+@media (min-width: 900px) { #kidreq { bottom: 16px; left: 236px; } }
+
+/* simple mode: no menus, big buttons */
+body.simple #nav, body.simple #navbar, body.simple #subnav, body.simple #chatfab, body.simple .fab { display: none !important; }
+body.simple #shell { flex-direction: column; }
+.simplewrap { max-width: 920px; } .simplewrap h1 { font-size: 34px; margin: 12px 0 18px; }
+.simplegrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 16px; }
+.simpletile { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 12px; min-height: 170px; border-radius: 28px; color: #fff; text-decoration: none; font-size: 24px; font-weight: 700; box-shadow: 0 6px 18px rgba(0,0,0,.3); } .simpletile svg { width: 64px; height: 64px; }
+#simplehome { position: fixed; left: 14px; bottom: calc(env(safe-area-inset-bottom, 0px) + 14px); z-index: 60; display: flex; align-items: center; gap: 10px; padding: 14px 24px; border-radius: 32px; background: var(--accent); color: var(--accent-t, #fff); font-size: 22px; font-weight: 700; text-decoration: none; box-shadow: 0 6px 18px rgba(0,0,0,.4); } #simplehome[hidden] { display: none; } #simplehome svg { width: 30px; height: 30px; }