fix(csrf): enable newsletter subscription from mobile

CRITICAL FIX: Newsletter subscription was returning "Forbidden" error
because the CSRF protection was incorrectly configured.

Root cause:
- CSRF cookie was set with httpOnly: true
- JavaScript cannot read httpOnly cookies
- Frontend couldn't extract token to send in X-CSRF-Token header
- Double-submit CSRF pattern requires client to read the cookie

Changes:
- csrf-protection.middleware.js: Set httpOnly: false (required for double-submit pattern)
- blog.js: Extract CSRF token from cookie and include in X-CSRF-Token header

Security Note: This is the correct implementation per OWASP guidelines
for double-submit cookie CSRF protection. The cookie is still protected
by SameSite: strict and domain restrictions.

Fixes: #newsletter-subscription-forbidden-mobile

.claude/session-state.json

@@ -43,8 +43,8 @@
       "last_deliberation": null
     },
     "FileEditHook": {
-      "timestamp": "2025-10-24T03:32:50.799Z",
+      "timestamp": "2025-10-24T03:42:14.478Z",
-      "file": "/home/theflow/projects/tractatus/public/js/admin/submission-modal-enhanced.js",
+      "file": "/home/theflow/projects/tractatus/src/middleware/csrf-protection.middleware.js",
       "result": "passed"
     },
     "FileWriteHook": {
@@ -58,25 +58,25 @@
     "tokens": 30000
   },
   "alerts": [],
-  "last_updated": "2025-10-24T03:32:50.799Z",
+  "last_updated": "2025-10-24T03:42:14.478Z",
   "initialized": true,
   "framework_components": {
     "CrossReferenceValidator": {
       "message": 0,
       "tokens": 0,
-      "timestamp": "2025-10-24T03:35:34.228Z",
+      "timestamp": "2025-10-24T03:42:14.476Z",
-      "last_validation": "2025-10-24T03:35:34.228Z",
+      "last_validation": "2025-10-24T03:42:14.476Z",
-      "validations_performed": 951
+      "validations_performed": 957
     },
     "BashCommandValidator": {
       "message": 0,
       "tokens": 0,
       "timestamp": null,
-      "last_validation": "2025-10-24T03:35:34.229Z",
+      "last_validation": "2025-10-24T03:42:26.291Z",
-      "validations_performed": 584,
+      "validations_performed": 589,
-      "blocks_issued": 62
+      "blocks_issued": 66
     }
   },
-  "action_count": 584,
+  "action_count": 589,
   "auto_compact_events": []
 }

public/js/blog.js

@@ -571,10 +571,17 @@ function setupNewsletterModal() {
       submitBtn.textContent = 'Subscribing...';
 
       try {
+        // Get CSRF token from cookie
+        const csrfToken = document.cookie
+          .split('; ')
+          .find(row => row.startsWith('csrf-token='))
+          ?.split('=')[1];
+
         const response = await fetch('/api/newsletter/subscribe', {
           method: 'POST',
           headers: {
-            'Content-Type': 'application/json'
+            'Content-Type': 'application/json',
+            'X-CSRF-Token': csrfToken || ''
           },
           body: JSON.stringify({
             email,

src/middleware/csrf-protection.middleware.js

@@ -79,7 +79,7 @@ function setCsrfToken(req, res, next) {
     const isSecure = req.secure || req.headers['x-forwarded-proto'] === 'https';
 
     res.cookie('csrf-token', token, {
-      httpOnly: true,
+      httpOnly: false,  // Must be false for double-submit pattern (client needs to read it)
       secure: isSecure && process.env.NODE_ENV === 'production',
       sameSite: 'strict',
       maxAge: 24 * 60 * 60 * 1000  // 24 hours