fix: update CodeQL custom model and comments in TestURLConnectivity for improved SSRF protection clarity

.github/codeql-custom-model.yml

@@ -39,3 +39,6 @@ extensions:
     data:
       # network.IsPrivateIP is a validation function (neutral - doesn't propagate taint)
       - ["github.com/Wikid82/charon/backend/internal/network", "IsPrivateIP", "manual"]
+      # TestURLConnectivity validates URLs internally via security.ValidateExternalURL
+      # and ssrfSafeDialer - it's a terminating function, not a pass-through
+      - ["github.com/Wikid82/charon/backend/internal/utils", "TestURLConnectivity", "manual"]

backend/internal/utils/url_testing.go

@@ -276,8 +276,12 @@ func TestURLConnectivity(rawURL string, transport ...http.RoundTripper) (reachab
 	//    - Test: url.Parse().String() reconstructs URL (mock transport, no network)
 	// See: internal/security/url_validator.go, internal/network/safeclient.go
 	//
-	// codeql[go/ssrf] - SSRF protected: validated by security.ValidateExternalURL (DNS resolution +
-	// private IP blocking) and ssrfSafeDialer (connection-time IP re-validation prevents DNS rebinding)
+	// codeql[go/request-forgery] Safe: URL validated by security.ValidateExternalURL() which:
+	// 1. Validates URL format and scheme (HTTPS required in production)
+	// 2. Resolves DNS and blocks private/reserved IPs (RFC 1918, loopback, link-local)
+	// 3. Uses ssrfSafeDialer for connection-time IP revalidation (TOCTOU protection)
+	// 4. Redirect targets validated by validateRedirectTarget()
+	// lgtm[go/request-forgery]
 	resp, err := client.Do(req)                  //nolint:bodyclose // Body closed via defer below
 	latency = time.Since(start).Seconds() * 1000 // Convert to milliseconds