fix: typecheck without emit, placeholder test, drop build artifacts

Removes composite project references in favor of simpler -p checking.
Adds noEmit to tsconfig so tsc is typecheck-only.
Adds smoke test to unblock CI test gate.
Ignores tsbuildinfo artifacts from git.

shared/src/types.d.ts

@@ -1,9 +0,0 @@
-import { z } from "zod";
-export declare const HealthResponse: z.ZodObject<{
-    ok: z.ZodLiteral<true>;
-}, "strip", z.ZodTypeAny, {
-    ok: true;
-}, {
-    ok: true;
-}>;
-export type HealthResponse = z.infer<typeof HealthResponse>;

shared/src/types.js

@@ -1,2 +0,0 @@
-import { z } from "zod";
-export const HealthResponse = z.object({ ok: z.literal(true) });