Add DependencyProvider and Lifecycle classes, along with utility types for time and data units. Implemented assertUnreachable for exhaustive checks in Lifecycle mapping.

src/lang/assertUnreachable.ts

@@ -0,0 +1,3 @@
+export default function assertUnreachable(x: never): never {
+  throw new Error(`Unreachable code: [${x}]`);
+}