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/@hono/node-server/dist/conninfo.d.ts

@@ -0,0 +1,10 @@
+import { GetConnInfo } from 'hono/conninfo';
+
+/**
+ * ConnInfo Helper for Node.js
+ * @param c Context
+ * @returns ConnInfo
+ */
+declare const getConnInfo: GetConnInfo;
+
+export { getConnInfo };