fix(form-field): sync heights inside fieldset (#DS-5370)

[NikGurev]

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[NikGurev]

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Pull request overview

This PR fixes a 1px “seam” regression in kbq-fieldset groups by ensuring kbq-form-field and adjacent controls (e.g., outline buttons) resolve to the same pixel-snapped height after resize/subpixel recalculation, and adds an E2E assertion that specifically exercises fractional device pixel ratios.

Changes:

• Force kbq-form-field height within kbq-fieldset to use the single height token and propagate that height down to the form-field container.
• Add a Playwright E2E check that compares form-field container and button bounding boxes at fractional deviceScaleFactor values (1.5x, 2.5x).
• Surface the new “fieldset + button” example in the form-field dev examples page.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/components/form-field/fieldset.scss	Forces token-based height synchronization for form-fields inside fieldsets and propagates 100% height to inner content/container.
packages/components/form-field/e2e.playwright-spec.ts	Adds fractional-DPR coverage to catch border seam regressions that don’t reproduce at 1x DPR.
packages/components-dev/form-field/module.ts	Includes and renders the new fieldset-with-button docs example in the dev examples view.

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