fix(lit): add updateBoundData helper and use it in interactive v0.8 widgets

[ppazosp]

Supersedes #1022 and #1034, which were closed after I accidentally deleted my fork. This PR merges both into a single clean branch rebased on current main.

Description

Adds a updateBoundData() helper to the Root base class that encapsulates the setData() + requestUpdate() pattern, and wires up all interactive v0.8 widgets (Slider, TextField, DateTimeInput, CheckBox) to use it.

Root cause: these components call processor.setData() to update the data model, but never requestUpdate(), so the signal change from SignalMap.set() is not picked up by SignalWatcher and render() is never called again. Other components bound to the same data path will not reflect the new value. Visible in Slider (the <span> showing the current value stays stuck), latent in the others because native <input> elements display typed characters regardless of Lit re-renders.

Fix: Centralize the setData() + requestUpdate() pattern in Root.updateBoundData() and migrate all four components to use it. Consistent with the existing pattern in MultipleChoice (multiple-choice.ts:308).

Also removes an unused Types import from the Slider.

Closes #597
Fixes #1023

Pre-launch Checklist

• I signed the CLA.
• I read the Contributors Guide.
• I read the Style Guide.
• I have added updates to the CHANGELOG.
• I updated/added relevant documentation.
• My code changes (if any) have tests.

[gemini-code-assist]

Code Review

This pull request refactors the Checkbox, DateTimeInput, Slider, and TextField components to utilize a new shared updateBoundData helper method in the Root class, streamlining data updates and ensuring consistent calls to requestUpdate(). Feedback suggests enhancing the updateBoundData method with a check for this.component to avoid unnecessary processing and redundant updates when the component is not fully initialized.

[gemini-code-assist]

The updateBoundData helper should verify that this.component is not null before proceeding. While processor.setData includes an internal check and logs a warning, explicitly checking it here prevents an unnecessary call and a redundant requestUpdate() when the component context is missing. This ensures the helper only executes when the component is fully initialized and attached to a node.

Suggested change

	protected updateBoundData(relativePath: string, value: DataValue) {
	if (!this.processor) {
	return;
	}
	this.processor.setData(
	this.component,
	relativePath,
	value,
	this.surfaceId ?? A2uiMessageProcessor.DEFAULT_SURFACE_ID
	);
	this.requestUpdate();
	}
	protected updateBoundData(relativePath: string, value: DataValue) {
	if (!this.processor || !this.component) {
	return;
	}
	this.processor.setData(
	this.component,
	relativePath,
	value,
	this.surfaceId ?? A2uiMessageProcessor.DEFAULT_SURFACE_ID
	);
	this.requestUpdate();
	}