feat(data): optional preload scheduler for AsyncDataService.createLazy

[kunalkindra]

What

Adds an optional third options argument to AsyncDataService.createLazy with a preload scheduler:

interface CreateLazyOptions {
  preload?: (warm: () => void) => void;
}

It is invoked once when the factory creates a lazy service instance, receiving a warm callback that eagerly triggers the real load — constructing the service before its first property is touched. Fully backward compatible: omit options (or options.preload) and the existing load-on-first-touch behavior is unchanged.

Why

A lazy service loads only when its first property is accessed. That keeps heavy imports out of the initial bundle, but the very first send / read / call pays for the load — and when that first touch happens right before the page tears down (e.g. an analytics event fired immediately before a navigation), the load can lose the race and the call is dropped.

preload closes that gap without giving up laziness. The caller owns the policy (when to warm — at browser idle, eagerly, after first input), while createLazy owns the mechanism (invoking load and memoizing). Because loading is idempotent, warm is safe to call any number of times and dedupes with the first real property access. The framework stays environment-agnostic — browser concerns like requestIdleCallback live in the caller's scheduler:

const createLazyAnalytics = AsyncDataService.createLazy(
  () => import('./analytics').then(m => m.create()),
  { send: 'fn:void', pageload: 'fn:void' },
  { preload: (warm) => requestIdleCallback(warm) }
);

Tests

Five new cases in create-lazy.test.ts: no-load without the option, scheduler invoked with warm on instance creation, warm loads before any property touch, warm dedupes with the first real touch, queued calls still drain after a preload. create-lazy.md documents the option. Local pnpm typecheck, pnpm lint, check:workspace, and the full data-package test suite (44/44) pass.