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>

server/src/app.js

@@ -9,15 +9,28 @@ require('dotenv').config()
 
 const apiRouter = require('./router/api.router')
 const createLogger = require('./utils/logger')
+const { applyTrustProxy, trustProxyDebug } = require('./utils/trustProxy')
+const botScore = require('./middleware/botScore')
 
 const httpLog = createLogger('http')
 const errLog = createLogger('error')
 
 const app = express()
 
-// Behind Pangolin: trust the first proxy so req.secure (for the cookie flag),
-// req.ip (activity log / rate limiting) reflect the X-Forwarded-* headers.
-app.set('trust proxy', 1)
+// Behind Pangolin: trust the forwarding proxy so req.secure (cookie flag) and
+// req.ip (activity log, rate limiting, backoff, bot-ban) reflect the real client
+// from X-Forwarded-*. Configurable via TRUST_PROXY; defaults to a single hop and
+// never a blanket `true` (which would let clients spoof their IP). Must run
+// before any middleware that reads req.ip.
+applyTrustProxy(app)
+
+// Optional trust-proxy diagnostics (off unless DEBUG_TRUST_PROXY is set). Before
+// the bot guard so it logs scanner/junk source IPs too.
+app.use(trustProxyDebug)
+
+// Bot / scanner guard — mounted first (before helmet/routing) so banned IPs and
+// obvious scanner probes are 404'd immediately without reaching real handlers.
+app.use(botScore.guard)
 
 // Security headers. CSP is left off here and will be tuned for the React SPA in
 // the frontend phase; the rest of helmet's protections stay enabled.