feat(ui): dispatch validation events from TextField

[dmandar]

This PR introduces the a2ui-validation-input event to the
TextField
component to bubble validation state changes.

Changes
TextField (
text-field.ts
):
Added dispatch of a2ui-validation-input on every input event.
Payload: { componentId, value, valid: boolean }.
Reason: Native invalid events do not cross the Shadow DOM boundary. This custom event allows parent components (like the Shell) to observe real-time validation status.
Component Gallery (
component-gallery.ts
):
Added a listener for a2ui-validation-input at the document root.
Logs validation events to both the Console and the internal Debug Panel for visual verification.
Verification
Verified manually in the Component Gallery:
Typing in "TextField (Regex)" now triggers logs in the Debug Panel.
Valid/Invalid states strictly match the regex rules.

Pre-launch Checklist

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

If you need help, consider asking for advice on the discussion board.

[gemini-code-assist]

Code Review

This pull request introduces a new a2ui-validation-input event dispatched from the TextField component to communicate validation state changes. The changes look good and achieve the goal. I've added a couple of minor suggestions to improve code style and robustness.

[ditman]

Comment about having a specific, shared type for the failed/passed validation event in web_core!

[ditman]

This LGTM, but I really think we shouldn't reexport from web_core. Instead, we should re-export from the lit renderer Events namespace.

(There's a similar problem to this with the styles. The Lit renderer only reexports the ones coming from web_core, instead of its internal version, so application users that want to use the basic styling for their own components, must use unsafeCSS, but that's a fix for another day :P)

[ditman]

Instead of importing and renaming here, how about exporting these events from web_core directly from ./events/events.js so they become part of the Events namespace offered by the lit renderer?

I think it's a little bit of an anti-pattern to re-export directly from web_core (unless you're coding an actual renderer?)

[ditman]

I think this won't work as is, because there's more stuff being exported from styles/index (like a merge function). Let's leave this part for another PR, so we land the validation events cleanly!