feat: restyle KvChip to the 2026 spec

[eddieferrer]

Ticket: https://kiva.atlassian.net/browse/CIT-4883

Figma

Summary

• KvChip is now outlined by default and fills on hover, rather than filled by default.
  Verified against the Figma spec by measuring the rendered element rather than reading
  class names: #ffffff surface, #edf4f1 hover, #223829 text and icon, 1px #c4c4c4
  border, 8px radius, 16x8 padding, 8px gap, 16/22 type at weight 300. Every value
  matches.
• Colors are fixed rather than themable, per design: a chip looks the same on every
  surface. Every value in the spec has an exact static token, so no hardcoded hex was
  needed — tw-bg-white, hover:tw-bg-eco-green-1, tw-text-eco-green-4,
  tw-border-gray-300. The Themes story renders the chip inside all five theme
  providers to show it does not vary.
• The wrapper div is gone, so the root is the button itself. It also gains
  type="button", which it was missing.
• First tests this component has had: the fixed styling, a guard that no themable color
  class creeps back in, the emit, the button-as-root structure, jest-axe, and a
  regression test for an undeclared @click still falling through — FilterChips in
  cms-page-server relies on that.

The second commit reverses the first on the themable question. The first version used
themable tokens because every spec value happens to land on one; design then confirmed
the chip should be fixed. Worth knowing the themable version also had a real bug that the
Themes story caught: border-tertiary resolves to #FFFFFF in the marigold and stone
themes, so the chip would have had no visible outline on those surfaces. Fixed colors
retire that problem entirely.

Not an API break

click-chip is unchanged and a consumer's plain @click still fires, so this is a minor.
The visual change is large though, and Chromatic diffs on every chip are the point rather
than noise.

Consumer follow-ups

Three live call sites exist, all of which get simpler:

• CIT-4889 (cms-page-server) — FilterChips has :deep(button) forcing
  tw-bg-gray-200 and border-radius: 8px, plus :deep(button > div) shrinking the label
  to 14px. All three are now dead: 8px is the spec, the grey approximated a neutral chip,
  and the slot's wrapper div no longer exists. EmailDomainInput wraps its label in
  <h4 class="tw-text-upper">. Consumers should not be overriding the chip's text size, so
  those come out and both call sites take the spec's 16px.
• CIT-4888 (ui) — not a version bump. ui never used this component. It has a local
  KvChipClassic used once in LoanSearchFilters, and a local KvChip that nothing
  imports at all. That ticket is a migration plus deleting dead code, and note
  KvChipClassic emits click where the library emits click-chip.

[eddieferrer]

Design confirmed the chip should not be themeable here: https://www.figma.com/design/TPmBUB4olYPMF6glEhBGDG/Ecosystem-2026--WIP-?node-id=20961-22768#1919728053