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/qs/lib/index.js

@@ -0,0 +1,11 @@
+'use strict';
+
+var stringify = require('./stringify');
+var parse = require('./parse');
+var formats = require('./formats');
+
+module.exports = {
+    formats: formats,
+    parse: parse,
+    stringify: stringify
+};