Implement OWASP ASVS L1 security remediation (Phases 0-2)

Auth: Add requireAuth/requireAdmin guards with JWT cookie verification,
member status checks (suspended/cancelled = 403), and admin role
enforcement. Apply to all admin, upload, and payment endpoints. Add
role field to Member model.

CSRF: Double-submit cookie middleware with client plugin. Exempt
webhook and magic-link verify routes.

Headers: X-Content-Type-Options, X-Frame-Options, X-XSS-Protection,
Referrer-Policy, Permissions-Policy on all responses. HSTS and CSP
(Helcim/Cloudinary/Plausible sources) in production only.

Rate limiting: Auth 5/5min, payment 10/min, upload 10/min, general
100/min via rate-limiter-flexible, keyed by client IP.

XSS: DOMPurify sanitization on marked() output with tag/attr
allowlists. escapeHtml() utility for email template interpolation.

Anti-enumeration: Login returns identical response for existing and
non-existing emails. Remove 404 handling from login UI components.

Mass assignment: Remove helcimCustomerId from profile allowedFields.

Session: 7-day token expiry, refresh endpoint, httpOnly+secure cookies.

Environment: Validate required secrets on startup via server plugin.
Remove JWT_SECRET hardcoded fallback.

server/middleware/03.rate-limit.js

@@ -0,0 +1,65 @@
+import { RateLimiterMemory } from 'rate-limiter-flexible'
+
+// Strict rate limit for auth endpoints
+const authLimiter = new RateLimiterMemory({
+  points: 5,     // 5 requests
+  duration: 300, // per 5 minutes
+  keyPrefix: 'rl_auth'
+})
+
+// Moderate rate limit for payment endpoints
+const paymentLimiter = new RateLimiterMemory({
+  points: 10,
+  duration: 60,
+  keyPrefix: 'rl_payment'
+})
+
+// Light rate limit for upload endpoints
+const uploadLimiter = new RateLimiterMemory({
+  points: 10,
+  duration: 60,
+  keyPrefix: 'rl_upload'
+})
+
+// General API rate limit
+const generalLimiter = new RateLimiterMemory({
+  points: 100,
+  duration: 60,
+  keyPrefix: 'rl_general'
+})
+
+function getClientIp(event) {
+  return getHeader(event, 'x-forwarded-for')?.split(',')[0]?.trim()
+    || getHeader(event, 'x-real-ip')
+    || event.node.req.socket.remoteAddress
+    || 'unknown'
+}
+
+const AUTH_PATHS = new Set(['/api/auth/login'])
+const PAYMENT_PREFIXES = ['/api/helcim/']
+const UPLOAD_PATHS = new Set(['/api/upload/image'])
+
+export default defineEventHandler(async (event) => {
+  const path = getRequestURL(event).pathname
+  if (!path.startsWith('/api/')) return
+
+  const ip = getClientIp(event)
+
+  try {
+    if (AUTH_PATHS.has(path)) {
+      await authLimiter.consume(ip)
+    } else if (PAYMENT_PREFIXES.some(p => path.startsWith(p))) {
+      await paymentLimiter.consume(ip)
+    } else if (UPLOAD_PATHS.has(path)) {
+      await uploadLimiter.consume(ip)
+    } else {
+      await generalLimiter.consume(ip)
+    }
+  } catch (rateLimiterRes) {
+    setHeader(event, 'Retry-After', Math.ceil(rateLimiterRes.msBeforeNext / 1000))
+    throw createError({
+      statusCode: 429,
+      statusMessage: 'Too many requests. Please try again later.'
+    })
+  }
+})