feat: establish TypeScript-aware frontend tooling

tests/unit/runtime-adapters.test.js

@@ -10,7 +10,7 @@ const runtime = {
     AUTH_MODE: "demo",
   },
 };
-const release = {
+const release = /** @type {const} */ ({
   schemaVersion: 1,
   appVersion: "0.1.0",
   buildId: "build-a",
@@ -20,7 +20,7 @@ const release = {
   assetManifestHash: "hash-a",
   releaseId: "release-a",
   builtAt: "2026-07-25T00:00:00Z",
-};
+});
 
 describe("runtime adapter composition", () => {
   it("constructs the local demo seam and infrastructure adapters", async () => {