feat(stdlib): new modules + eslint/tsconfig migration

- Add array/async/etc. modules and type tests; migrate to eslint flat config
  and composite tsconfig (vitest typecheck enabled).
- Fix PubSub.emit to snapshot listeners before iterating (stable EventEmitter
  semantics; avoids invoking listeners added during the same emit).

core/stdlib/eslint.config.ts

@@ -0,0 +1,3 @@
+import { base, compose, imports, stylistic, typescript } from '@robonen/eslint';
+
+export default compose(base, typescript, imports, stylistic);