Family mode: multiple profiles without passwords

[benSlaughter]

Enable multiple children on one device — each with their own garden, progress, and achievements. No passwords needed.

This is Mode 2 (Family) of the 3-tier profile system. See docs/ROADMAP.md.

How it works

• Admin sets profile_mode to family in settings (default remains single)
• On app launch, a "Who are you?" screen shows avatar cards with names
• Child taps their card → goes straight to their dashboard (no password)
• Each profile has separate: progress, achievements, unlocks, garden state
• Admin creates/edits/deletes profiles (name + avatar)
• Designed for 2–5 profiles (a family, not a classroom)

"Who are you?" screen

• Full-screen, friendly, colourful
• Big avatar cards in a grid (2–3 per row)
• Each card shows: avatar illustration, child name, a tiny garden preview or streak count
• Tapping a card sets a session cookie for that profile and redirects to home
• No password, no typing — just tap

Database changes

• profiles table already exists with name and avatar columns
• Add settings key: profile_mode (single | family | school)
• All existing API routes already take profile_id — make it dynamic from session

Admin UI

• New "Profiles" section in admin dashboard
• Add/edit/delete profiles
• Assign avatar from a preset list
• View per-profile progress summary

Prerequisites

• Admin: set learner profile name #27 (profile name in admin) — builds the name editing foundation
• Character avatar system #14 (character avatars) — provides the avatar illustrations

Migration

• Existing data stays on profile 1
• New profiles start with a fresh garden