Model permissions as (app, role) and name passkeys from their AAGUID

Two changes to the admin module, both made now because it is not deployed yet
and neither is free later.

Permissions were "an app", with a `role` column reserved for a future
fine-grained model. Reviewing whether that reservation was enough found three
problems:

- Every row was written with role = 'admin', hardcoded, and the column
  defaulted to it. On a `tickets` row that reads as "tickets administrator"
  when it only ever meant "has access", and once real roles existed there
  would have been no way to tell an old plain grant from a deliberate one.
- The role never left the database. /admin/me, the user list, the user detail
  and both write endpoints all spoke apps: AppName[]. Adding roles would have
  been a breaking change to /admin/me - and after the cutover that endpoint
  has two more consumers, turning a local edit into a coordinated deploy of
  three apps.
- The key (user_id, app) allowed one role per app, i.e. a tier rather than a
  set of capabilities. Choosing later means an ALTER on a live table.

So: the key is now (user_id, app, role), the role is `access`, and APP_ROLES
in admin.schema.ts is the contract - a role not listed there is rejected with
400 rather than written. permissions: [{app, role}] is on the wire alongside
the derived apps: AppName[], which is kept because the three frontends only
ever ask "may I show this app?". Both write endpoints accept either shape, and
the invitation column (now `permissions`) is parsed leniently: invitations live
seven days, so a deploy that changes the shape has in-flight rows in the old
one. requireAppAccess(app, role?) takes an optional role; nothing passes one
yet.

countActiveAdminsForUpdate now counts DISTINCT users rather than rows. With
several roles per app, counting rows would make a single admin holding two
roles look like two admins and defeat the last-admin guard at exactly the
moment it matters.

Separately, passkey registration now fills `name` from the authenticator's
AAGUID via registration.afterVerification and better-auth's own
getAuthenticatorName, yielding "1Password", "iCloud Keychain", "Windows Hello".
Without it the column stayed NULL and the account page could only label every
passkey "Passkey" - useless when someone has to remove the one on the device
they just lost. A client-supplied name still wins; an unknown AAGUID still
leaves it blank.

148 unit tests (up from 131, including the new admin.schema.test.ts) and 41
integration tests pass. The integration suite applies sql/admin/001_init.sql,
so the new key is exercised rather than trusted.

No production migration is needed - the module is not deployed. An existing dev
database needs three statements: set role = 'access', drop and re-add the
primary key, rename invitations.apps to permissions.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

CLAUDE.md

@@ -46,9 +46,17 @@ other domain keeps the `mariadb` driver), mounted at `/admin/auth/*` for the aut
 and `/admin` for the JSON routes. Sessions are httpOnly cookies scoped to
 `.nachklang.art`, so one sign-in covers every app. Accounts are **invite-only** — public
 sign-up is disabled, and `invitations.plugin.ts` is the only code that creates users.
-Permissions are per app in `user_app_permissions`; `requireAppAccess(app)` in
-`admin.middleware.ts` is the single authenticator, and it queries the database on every
-request (no cookie cache) so disabling a user takes effect at once. `ADMIN_BOOTSTRAP_EMAIL`
+A permission is **(app, role)** in `user_app_permissions`, keyed on
+`(user_id, app, role)` so one user can hold several roles per app. `access` is the only role
+today and means "may use this app at all"; `APP_ROLES` in `admin.schema.ts` is the contract,
+and a role not listed there is rejected rather than written. `requireAppAccess(app)` in
+`admin.middleware.ts` is the single authenticator - it takes an optional second argument to
+narrow to one role, and queries the database on every request (no cookie cache) so disabling
+a user takes effect at once. Two things to know before touching this: any count of admins
+must count **distinct users**, not permission rows, or a single admin with two roles reads as
+two and the last-admin guard stops guarding; and both write endpoints accept
+`{permissions: [{app, role}]}` as well as the older `{apps: ['tickets']}`, which means the
+same at the `access` role. `ADMIN_BOOTSTRAP_EMAIL`
 makes sure someone can always get in on a fresh database.
 
 *Legacy calendar* — unchanged: users need a `@nachklang.art` email, and after activation