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/jose/dist/webapi/lib/is_object.js

@@ -0,0 +1,14 @@
+const isObjectLike = (value) => typeof value === 'object' && value !== null;
+export function isObject(input) {
+    if (!isObjectLike(input) || Object.prototype.toString.call(input) !== '[object Object]') {
+        return false;
+    }
+    if (Object.getPrototypeOf(input) === null) {
+        return true;
+    }
+    let proto = input;
+    while (Object.getPrototypeOf(proto) !== null) {
+        proto = Object.getPrototypeOf(proto);
+    }
+    return Object.getPrototypeOf(input) === proto;
+}