feat: add security headers to caddyfile

.jules/sentinel.md

@@ -0,0 +1,4 @@
+## 2024-06-01 - [Missing Security Headers]
+**Vulnerability:** The web application served by Caddy was missing essential security headers, making it more vulnerable to Clickjacking and MIME-sniffing attacks.
+**Learning:** Security headers should be explicitly configured in the reverse proxy/web server (Caddy in this case) since they are not typically added by default application servers or front-end frameworks.
+**Prevention:** Always ensure standard security headers (`X-Frame-Options`, `X-Content-Type-Options`, `Referrer-Policy`, etc.) are configured globally in the Caddyfile or equivalent web server configuration for all incoming requests.

Caddyfile

@@ -6,6 +6,12 @@
 :80 {
   encode zstd gzip
 
+  header {
+    X-Frame-Options "DENY"
+    X-Content-Type-Options "nosniff"
+    Referrer-Policy "strict-origin-when-cross-origin"
+  }
+
   @mcp path /mcp
   handle @mcp {
     reverse_proxy 127.0.0.1:3001