Fix race conditions in component rendering and updates

This ticket addresses two related race conditions that were causing flaky tests in test/playwright/component/component/Base.spec.mjs.

1. Colliding Parent/Child VDOM Updates

Problem: A race condition can occur when a parent and a direct child component receive update requests simultaneously. The collision detection in VdomLifecycle.mjs#hasUpdateCollision() failed to identify a conflict when the parent's updateDepth and the child's distance were both 1. This allowed updates to run in parallel, leading to unpredictable DOM state.

Solution: Modify hasUpdateCollision() to use <= instead of <:

hasUpdateCollision(updateDepth, distance) {
    return updateDepth === -1 ? true : distance <= updateDepth;
}

This ensures a direct child update is correctly queued when its parent is already updating.

2. Test Synchronization with Initial Render

Problem: The test was starting its updates before the component's asynchronous initialization process was fully complete. await page.waitForSelector() is not sufficient to guarantee the component is in a stable, idle state ready for updates. This caused updates to be lost or to conflict with the initial render itself.

Solution: Make the test more robust by synchronizing with the application state. Before triggering updates, force the test to wait for the initial state to be rendered in the DOM by reading a property from the relevant elements.

Example change in test/playwright/component/component/Base.spec.mjs:

await page.waitForSelector('.neo-button');

// Add these checks to wait for the initial render to be fully complete
const initialToolbarHeight = await page.locator(`#${toolbarId}`).evaluate(el => el.style.height);
const initialButtonText    = await page.locator(`#${buttonId}`).evaluate(el => el.firstChild.innerHTML);

expect(initialToolbarHeight).toBe('200px');
expect(initialButtonText).toBe('hello');

// Now it is safe to proceed with updates
await page.evaluate(async ({buttonId, toolbarId}) => {
    // ...
});