Player accounts backend: schema, registration, self-service, SSO provision

- Widen users.role enum to include 'player'; make password_hash nullable;
  add email/email_verified/status/last_login_ip; pin username _ci collation.
- POST /auth/register (honeypot + registerLimiter + botScore, reserved-name
  blocklist, duplicate->409, auto-login). player_registration setting gates it.
- SSO auto-provision in finishLogin (setting-gated); return/portal-aware SSO
  redirects for the player portal; status refusal on login + requireAuth.
- New /player self-service group (account, change username/password, TOTP,
  identities), reusing account.controller; accountChangeLimiter.
- Admin: 'player' role + status/email on user create/update, role/status audit,
  player_registration enum validation, derived public registration flags.
- usernamePolicy module (reserved, sanitize, derive, dedup) + unit tests;
  extend SSO callback tests. 133 server tests green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019rao86n5cXpwAyjdBFEshV

server/src/router/v1/v1.router.js

@@ -5,10 +5,12 @@ const v1Router = express.Router()
 const authRouter = require('./auth/auth.routes')
 const publicRouter = require('./public/public.routes')
 const adminRouter = require('./admin/admin.routes')
+const playerRouter = require('./player/player.routes')
 
 v1Router.use('/auth', authRouter)
 v1Router.use('/public', publicRouter)
 v1Router.use('/admin', adminRouter)
+v1Router.use('/player', playerRouter)
 // NOTE: /internal is intentionally NOT mounted here. Those routes return the
 // decrypted Discord bot token and must never share the public listener that
 // Pangolin proxies. They live on a separate, unpublished port via