feat: CRUD rate limit and improve security

internal/middleware/security_headers.go

@@ -0,0 +1,33 @@
+package middleware
+
+import (
+	"net/http"
+)
+
+// SecurityHeaders sets common security response headers on every response.
+// Note: HSTS is handled by Caddy at the reverse proxy layer.
+func SecurityHeaders() func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			h := w.Header()
+
+			h.Set("Content-Security-Policy",
+				"default-src 'self'; "+
+					"script-src 'self' 'unsafe-inline' https://www.googletagmanager.com; "+
+					"style-src 'self' 'unsafe-inline'; "+
+					"img-src 'self' data:; "+
+					"connect-src 'self' https://www.google-analytics.com; "+
+					"font-src 'self'; "+
+					"frame-ancestors 'none'; "+
+					"base-uri 'self'; "+
+					"form-action 'self'")
+
+			h.Set("X-Frame-Options", "DENY")
+			h.Set("X-Content-Type-Options", "nosniff")
+			h.Set("Referrer-Policy", "strict-origin-when-cross-origin")
+			h.Set("Permissions-Policy", "camera=(), microphone=(), geolocation=(), payment=()")
+
+			next.ServeHTTP(w, r)
+		})
+	}
+}