Replace inline locate-node link with design-system Button in ErrorGroupList.vue

## Summary
In `src/components/rightSidePanel/errors/ErrorGroupList.vue`, the execution-error item list renders an inline "locate node" control as a raw `` with hand-rolled Tailwind classes instead of the shared design-system `Button` component (`src/components/ui/button/Button.vue`).

This markup was moved verbatim from `TabErrors.vue` as part of the `ErrorGroupList` extraction and predates this PR, so the swap was intentionally deferred to keep the extraction behavior-preserving.

## Rationale
- Aligns with repository convention of using the shared `Button` component instead of raw `` elements for consistent styling/behavior.
- Swapping to `` changes how the inline locate link renders visually, so it needs a dedicated visual check rather than being bundled into an unrelated refactor PR.

## Affected areas
- `src/components/rightSidePanel/errors/ErrorGroupList.vue` (inline locate-node `` inside the execution-item list)

## Acceptance criteria
- [ ] Replace the raw `` used for locating a node in the execution-item list with the shared `Button` component (appropriate variant, e.g. `link` or `muted-textonly`).
- [ ] Visually verify the rendered control matches expected design (tooltip, truncation, hover/focus states) before/after the change.
- [ ] No behavior regression for click-to-locate functionality or accessibility (focus ring, keyboard interaction).

## References
- PR: https://github.com/Comfy-Org/ComfyUI_frontend/pull/13459
- Discussion: https://github.com/Comfy-Org/ComfyUI_frontend/pull/13459#discussion_r3532256872
- Requested by: @jaeone94