feat(provisioning): game-account signup, admin email invites, unlink (2.0)

Phase 5: the account-provisioning backend — link-only stays, plus hybrid
self-signup, an admin email-invite tool, and site-side unlink.

- uoLinkClient.createAccount / unlinkAccount (v2). Password is forwarded to the
  shard (hashed there) and never stored/logged; the end-user browser IP is passed
  for the shard's per-IP cap; actor is stamped server-side.
- Hybrid signup: POST /player/shard/account provisions a game account (its own
  username + password) for the signed-in user and mirrors the link locally. Gated
  by the new game_account_signup setting AND the shard's own mode (mapped 403/409/
  429/400/503). Serves both self-serve signup and the invite-accept game step.
- Email invites: user_invites table (sha256 token hash, single-use, expiring);
  invites model + admin CRUD (POST/GET/DELETE /admin/invites, admin-only) +
  mailer.sendInvite (falls back to returning the accept link if email is off);
  public token-gated accept (GET /auth/invite/:token, POST .../accept) creates the
  user at the invite's preset role and logs them in, bypassing the registration
  gate. Accept is race-safe (atomic single-use; rolls back the user if it loses).
- Admin unlink: DELETE /admin/users/:id/shard/link/:account (admin-only) + local
  mirror drop; account.unlinked ingest reconciles the mirror when a player runs
  [unlink in game. account.audit / account.unlinked are logged (admin channel
  only — never on the public SSE allowlist).

Tests: invites model (hashing, single-use, expiry, revoke) + account.* ingest
reconcile/visibility. Full suite 193/193; swagger regenerated.

Refs .plans/protocol2-integration.md (Phase 5).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/src/router/v1/admin/usersShard.controller.js

@@ -10,6 +10,8 @@
 const users = require('../../../model/users/users.model')
 const shardLinks = require('../../../model/shardLinks/shardLinks.model')
 const shardState = require('../../../model/shardState/shardState.model')
+const uoLinkClient = require('../../../utils/uoLinkClient')
+const activity = require('../../../model/activity/activity.model')
 const { salesForAccounts } = require('../../../utils/shardSales')
 
 const log = require('../../../utils/logger')('admin-user-shard')
@@ -101,4 +103,40 @@ async function getStanding(req, res) {
   }
 }
 
-module.exports = { getUser, listAccounts, getSales, getHouses, getOnline, getStanding }
+// DELETE /admin/users/:id/shard/link/:account — unlink a game account from this
+// user, site-side. `actor` is stamped from the session (never the browser). On
+// success the sidecar clears the WebsiteUserId tag on the shard and we drop the
+// local mirror so attribution stops immediately.
+async function unlinkAccount(req, res) {
+  const { account } = req.params
+  try {
+    const ctx = await accountsForUser(Number(req.params.id))
+    if (!ctx) return res.status(404).json({ message: 'Not found' })
+    // Only unlink an account actually linked to THIS user (avoid cross-user unlink).
+    if (!ctx.accounts.includes(account)) {
+      return res.status(404).json({ message: 'That account is not linked to this user.' })
+    }
+    const result = await uoLinkClient.unlinkAccount({ actor: req.user.username, account })
+    if (result.ok) {
+      await shardLinks.removeByAccount(account)
+      await activity.log({ req, userId: ctx.user.id, action: 'shard.account.unlink', detail: { account } })
+      log.info('game account unlinked', { account, userId: ctx.user.id, actor: req.user.username })
+      return res.json({ account, unlinked: true })
+    }
+    if (result.status === 403) return res.status(403).json({ message: 'That account is protected and cannot be unlinked.' })
+    if (result.status === 404) {
+      // Not linked on the shard — reconcile our mirror anyway so the two agree.
+      await shardLinks.removeByAccount(account)
+      return res.status(404).json({ message: 'That account is not linked.' })
+    }
+    if (result.status === 503 || result.status === 0) {
+      return res.status(503).json({ message: 'The game server is unavailable — try again shortly.' })
+    }
+    return res.status(502).json({ message: 'Could not reach the shard to unlink the account.' })
+  } catch (err) {
+    log.error('unlinkAccount', err)
+    return res.status(500).json({ message: 'Internal Server Error' })
+  }
+}
+
+module.exports = { getUser, listAccounts, getSales, getHouses, getOnline, getStanding, unlinkAccount }