feat(API-11): Route API calls through AgilitonAPI gateway

Add gateway-first pattern: when AGILITON_API_KEY is set, route all
external API calls through the gateway with X-API-Key auth. Falls back
to direct API access when gateway is unavailable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

node_modules/gopd/index.js

@@ -0,0 +1,15 @@
+'use strict';
+
+/** @type {import('.')} */
+var $gOPD = require('./gOPD');
+
+if ($gOPD) {
+	try {
+		$gOPD([], 'length');
+	} catch (e) {
+		// IE 8 has a broken gOPD
+		$gOPD = null;
+	}
+}
+
+module.exports = $gOPD;