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.

server/tsconfig.json

@@ -1 +1 @@
-{ "extends": "../tsconfig.base.json", "include": ["src", "test"], "references": [{ "path": "../shared" }] }
+{ "extends": "../tsconfig.base.json", "include": ["src", "test"] }