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/api/auth/login.post.js

@@ -19,19 +19,23 @@ export default defineEventHandler(async (event) => {
     });
   }
 
+  const GENERIC_MESSAGE = "If this email is registered, we've sent a login link.";
+
   const member = await Member.findOne({ email });
+
   if (!member) {
-    throw createError({
-      statusCode: 404,
-      statusMessage: "No account found with that email address",
-    });
+    // Return same response shape to prevent enumeration
+    return {
+      success: true,
+      message: GENERIC_MESSAGE,
+    };
   }
 
   // Generate magic link token
   const token = jwt.sign(
     { memberId: member._id },
     process.env.JWT_SECRET,
-    { expiresIn: "15m" }, // Shorter expiry for security
+    { expiresIn: "15m" },
   );
 
   // Get the base URL for the magic link
@@ -65,7 +69,7 @@ export default defineEventHandler(async (event) => {
 
     return {
       success: true,
-      message: "Login link sent to your email",
+      message: GENERIC_MESSAGE,
     };
   } catch (error) {
     console.error("Failed to send email:", error);