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/ajv-formats/dist/index.d.ts

@@ -0,0 +1,15 @@
+import { FormatMode, FormatName } from "./formats";
+import type { Plugin, Format } from "ajv";
+export { FormatMode, FormatName } from "./formats";
+export { LimitFormatError } from "./limit";
+export interface FormatOptions {
+    mode?: FormatMode;
+    formats?: FormatName[];
+    keywords?: boolean;
+}
+export type FormatsPluginOptions = FormatName[] | FormatOptions;
+export interface FormatsPlugin extends Plugin<FormatsPluginOptions> {
+    get: (format: FormatName, mode?: FormatMode) => Format;
+}
+declare const formatsPlugin: FormatsPlugin;
+export default formatsPlugin;