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/has-symbols/tsconfig.json

@@ -0,0 +1,10 @@
+{
+	"extends": "@ljharb/tsconfig",
+	"compilerOptions": {
+		"target": "ES2021",
+		"maxNodeModuleJsDepth": 0,
+	},
+	"exclude": [
+		"coverage"
+	]
+}