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/src/arrays/index.ts

@@ -1,5 +1,10 @@
 export * from './cluster';
 export * from './first';
+export * from './groupBy';
 export * from './last';
+export * from './partition';
+export * from './range';
 export * from './sum';
+export * from './toArray';
 export * from './unique';
+export * from './zip';