fix(security): harden 2FA setup, OIDC default role, and rate-limit fallback (v0.17.3-beta)

Address the actionable findings from an adversarial review:

- 2FA enrollment now requires the current password (/totp/setup), so a
  hijacked session or XSS can't enable TOTP and lock the real user out.
  SSO-only accounts (no local password) are told to set one first. Frontend
  collects the password before starting setup.
- OIDC config rejects default_role='admin': auto-provisioning unmatched users
  straight to admin is almost never intended — admin must come from an explicit
  group → role mapping.
- Rate limiter no longer fails fully open on a Redis outage. Redis calls are
  bounded by an 800ms timeout (the client uses maxRetriesPerRequest:null, so
  commands would otherwise hang, not throw), and on failure a per-process
  in-memory sliding-window fallback keeps /login and other limited endpoints
  throttled. Verified with Redis stopped: attempts throttle (429) instead of
  hanging or passing unlimited.

Findings intentionally not actioned: the "API-token auth is fire-and-forget"
report was a false positive (Express awaits next(), which is called inside the
promise), and the webhook DB-pool and JWT-revocation items are either
overstated or a separate architectural decision.

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

README.md

@@ -2,7 +2,7 @@
 
 A self-hosted, full-stack network management platform for MikroTik devices. Monitor, configure, and manage your entire MikroTik infrastructure — routers, switches, and wireless access points — from a single web interface.
 
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