feat(account): self-service account deletion, MODULE_API 1.20.0

ACCOUNT_DELETION.md phase 2 (core): a member deletes their own account on
the website, and the admin route runs the same procedure.

- DELETE /api/v1/auth/me/account: typed username, password always (AD7),
  and a 2FA or recovery code when 2FA is on. A wrong password or code is
  400, not 401 (AD12), so the app's refresh-on-401 never replays it.
  409 password_required and last_admin; the demo's shared logins are
  locked.
- auth/accountDeletion.js: module hooks first, then one transaction that
  reserves a staff username (reserved_usernames, AD9) and deletes the row,
  then a Teams reconcile, the audit entry (no username) and a notice to
  the old address (new protected template auth.account-deleted).
- MODULE_API 1.20.0: api.onUserDeleting({ userId, deletedBy }), before the
  delete, 10 s limit, cannot veto (AD10, AD11).
- utils/displayAuthor.js: a deleted account's username snapshots read
  "[deleted player]" to members and the stored name, marked, to staff
  (AD5, AD6). Used by the forum, the Reports queue, the guest list and
  the Team digest. A deleted account drops off Forum guests (AD13).
- Reserved names refuse at every username write, answered as "taken".
- Web: Delete my account on the player and staff Account pages; staff
  views mark "(deleted account)".
- OpenAPI regenerated; route manifest and engagement manifest regenerated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

server/src/utils/teamDigestWorker.js

@@ -42,6 +42,7 @@ const templates = require('../engagement/templates')
 const emailChannel = require('../engagement/emailChannel')
 const mailer = require('./mailer')
 const notify = require('./teamNotify')
+const { DELETED_PLAYER } = require('./displayAuthor')
 const log = require('./logger')('team-digest')
 
 const INTERVAL_MS = Number(process.env.TEAM_DIGEST_INTERVAL_MS) || 24 * 60 * 60 * 1000
@@ -127,7 +128,10 @@ async function sendOne(team, recipient, rule, now) {
     periodLabel: `${label}: ${posts.length} new post${posts.length === 1 ? '' : 's'}`,
     intro: `Since your last digest, ${posts.length} new post${posts.length === 1 ? '' : 's'} in ${label}:`,
     items: posts.map((p) => ({
-      heading: `${p.title} — ${p.author_username || 'someone'}`,
+      // A digest goes to members, who see a deleted author as "[deleted player]"
+      // (ACCOUNT_DELETION.md AD5). The post outlives its author on purpose; the
+      // name in it does not reach a member's inbox.
+      heading: `${p.title} — ${p.author_user_id === null ? DELETED_PLAYER : p.author_username || 'someone'}`,
       excerpt: notify.excerpt(p.body_html),
       url: notify.threadPath(team, p.thread_id),
     })),