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/zod/v4/locales/zh-CN.d.cts

@@ -0,0 +1,5 @@
+import type * as errors from "../core/errors.cjs";
+declare function _default(): {
+    localeError: errors.$ZodErrorMap;
+};
+export = _default;