Harden admin login: RBAC-safe controls, 2FA, bot-scoring, rate limits (#9)

Adds a layered set of protections around the admin login and the app edge.

Trust proxy (server/src/utils/trustProxy.js)
- Configurable via TRUST_PROXY; pin to the newt agent ("ptero") LAN IP so
  X-Forwarded-For is trusted ONLY from that peer. A blanket "true" is
  rejected (coerced to 1) to prevent XFF spoofing that would dodge every
  IP-based control. DEBUG_TRUST_PROXY logs peer/XFF/req.ip to re-verify the
  proxy IP without a redeploy. Documents the Omada static-reservation
  assumption.

Login throttling (server/src/middleware/loginProtection.js, rateLimit.js)
- express-slow-down progressive delay + the existing hard rate cap + a
  separate per-IP exponential backoff that persists across the rate window.
  All failures return one generic message (no user/pass disclosure).

Honeypot (login form + auth.controller)
- Hidden, plausibly-named field ("company"); a filled value fails
  generically and is scored as an unambiguous bot.

Optional per-user TOTP 2FA (speakeasy/qrcode)
- totp_secret/totp_enabled columns (+ idempotent migration). Self-service
  Account page: enroll via QR, confirm a code to enable, code-gated disable.
- Login is two-step for enrolled users: after the password, a short-lived
  signed challenge (stage:'totp', not a session) is required before the
  real session is issued.

Bot / scanner scoring + IP ban (server/src/middleware/botScore.js)
- Weighted CMS-scanner paths (this app uses none). Junk paths 404 FIRST,
  unconditionally — independent of score/ban state, so a scanner rotating
  through fresh Cloudflare IPs gets no free pass. /wp-admin/install.php is
  the top-weighted near-1-hit ban (worst offender in prod logs). Per-IP
  score with quiet-period decay temp-bans an IP from ALL routes once past a
  (deliberately low) threshold, to protect /admin from credential stuffing.
  Failed logins and honeypot hits feed the same score.
- Periodic sweep evicts stale, unbanned, quiet entries so the in-memory
  store can't grow unbounded; the interval is unref'd and cleared on
  graceful shutdown.

Tests: node --test suite (40) covering trust-proxy parsing + live req.ip
(incl. pinned-IP), rate limiter + exponential backoff, honeypot rejection,
TOTP verify (enabled/disabled) + challenge-isn't-a-session, bot-score
threshold/decay/ban + junk-404-independence + install.php + store sweep.

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

.env.example

@@ -28,6 +28,21 @@ JWT_EXPIRES_IN=1d
 COOKIE_SECURE=auto
 COOKIE_NAME=uomm_token
 
+# Reverse-proxy trust (req.ip / req.secure for rate limiting, backoff, bot-ban).
+# Path: client -> Pangolin -> newt agent "ptero" (separate VM) -> app. Pin this
+# to ptero's LAN IP (e.g. 10.0.0.42) so XFF is only trusted from ptero. Requires
+# a static DHCP reservation for ptero in Omada, else a lease change breaks it.
+# Integer hop count or "false" also accepted; a blanket "true" is rejected
+# (coerced to 1) to prevent X-Forwarded-For spoofing.
+TRUST_PROXY=1
+# Set to 1 to log raw peer address + X-Forwarded-For + resolved req.ip per
+# request (to verify/refresh ptero's IP without redeploying). Noisy; keep off.
+DEBUG_TRUST_PROXY=0
+
+# Optional TOTP two-factor (opt-in per user).
+TOTP_ISSUER=UOMysticmoon
+TOTP_CHALLENGE_TTL=5m
+
 # First admin bootstrap — created only if no users exist yet.
 # Set, run once, then you can blank these out.
 ADMIN_USERNAME=