Multiple people: an admin adds users and chooses which tabs each may use

- Accounts: the setup code (or an existing single-user install, migrated automatically) creates the admin;
  the admin adds people in Settings -> People and gives each a one-time invite code to enrol their own passkey
- Each person's tasks, NE Hub events and subscribe link, settings, calendar links, iCloud connection and Plex
  sign-in are private, stored in their own folder (/data/users/<id>/); Plex sign-in moved from browser cookies
  into that folder (encrypted), so it also follows them across devices
- Tab access is enforced by the server (403) and reflected in the app (nav, Home, Settings, search, /api/config
  hides addresses of tabs a person cannot use); browser storage is namespaced per person
- Admin tools: change tabs, invite a device, sign out everywhere (session epoch), turn off, make/remove admin,
  delete a person and their data; the last admin cannot be removed
- Sessions carry the person (uid.epoch.expiry.signature); old single-user cookies still work as the admin
- tools/users-test.js (83 checks: isolation, access limits, invites, sign-out/disable/delete, Plex and iCloud
  per person, migration) now runs in the Gitea workflow before the image is built

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

Dockerfile

@@ -2,7 +2,7 @@ FROM node:22-alpine
 WORKDIR /app
 COPY package.json package-lock.json ./
 RUN npm ci --omit=dev
-COPY server.js auth.js cal.js ics.js caldav.js tasks.js settings.js search.js ./
+COPY server.js auth.js cal.js ics.js caldav.js tasks.js settings.js search.js users.js admin.js vault.js ./
 COPY public ./public
 ENV PORT=8080 DATA_DIR=/data
 RUN mkdir -p /data && chown node:node /data