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-to-json-schema/dist/esm/parsers/literal.js

@@ -0,0 +1,21 @@
+export function parseLiteralDef(def, refs) {
+    const parsedType = typeof def.value;
+    if (parsedType !== "bigint" &&
+        parsedType !== "number" &&
+        parsedType !== "boolean" &&
+        parsedType !== "string") {
+        return {
+            type: Array.isArray(def.value) ? "array" : "object",
+        };
+    }
+    if (refs.target === "openApi3") {
+        return {
+            type: parsedType === "bigint" ? "integer" : parsedType,
+            enum: [def.value],
+        };
+    }
+    return {
+        type: parsedType === "bigint" ? "integer" : parsedType,
+        const: def.value,
+    };
+}