feat(ekko): add WithTrustOptions for CDN IP trust configuration

Allow callers to append additional echo.TrustOption values to the
default IP extraction configuration. This enables trusting CDN IP
ranges (e.g. Fastly) when extracting client IPs from X-Forwarded-For.

ekko/ekko.go

@@ -163,6 +163,7 @@ func (ek *Ekko) setup(ctx context.Context) (*echo.Echo, error) {
 		echo.TrustLinkLocal(false),
 		echo.TrustPrivateNet(true),
 	}
+	trustOptions = append(trustOptions, ek.extraTrustOptions...)
 	e.IPExtractor = echo.ExtractIPFromXFFHeader(trustOptions...)
 
 	if ek.otelmiddleware == nil {