feat(kit): render the chips with UiChip and UiButton

UiChip is a non-interactive label chip and renders the voice
card's chips. The pressable chips and pills are pressed toggles, so the
rail card chips, map source chips and city and place pills render through
UiButton with pressedClass, keeping their classes, attributes and the
classes other code adds. The pills now report aria-pressed.

src/ui/kit/UiChip.test.mjs

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+import { after, before, test } from 'node:test';
+import assert from 'node:assert/strict';
+import { installVueDom } from '../../testSupport/vueDom.mjs';
+
+let mount;
+let UiChip;
+let uninstall;
+before(async () => {
+  uninstall = installVueDom();
+  ({ mount } = await import('@vue/test-utils'));
+  UiChip = (await import('./UiChip.vue')).default;
+});
+after(() => uninstall());
+
+test('a chip is a span with the kit classes and Core’s', async () => {
+  const wrapper = mount(UiChip, {
+    attrs: { class: 'gev-voice-card-chip', 'data-tone': 'ok' },
+    slots: { default: 'ok' },
+  });
+  const chip = wrapper.get('span');
+  assert.deepEqual(chip.classes(), ['ui-chip', 'gev-voice-card-chip']);
+  assert.equal(chip.attributes('data-tone'), 'ok');
+  assert.equal(chip.text(), 'ok');
+  await wrapper.setProps({ selected: true, mono: true });
+  assert.ok(chip.classes().includes('ui-chip--selected'));
+  assert.ok(chip.classes().includes('ui-mono'));
+  wrapper.unmount();
+});

src/ui/kit/UiChip.vue

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+<script setup>
+// Core's chip, with @halfpixel/ui-vue UiChip's props and classes so the two
+// kits can merge: a label that says what something is, never a control.
+// Core styles it through the classes its callers pass; the kit classes carry
+// no Core styles yet. A chip that presses is a UiButton with pressedClass.
+defineProps({
+  selected: { type: Boolean, default: false },
+  mono: { type: Boolean, default: false },
+});
+</script>
+
+<template>
+  <span
+    class="ui-chip"
+    :class="{ 'ui-chip--selected': selected, 'ui-mono': mono }"
+  >
+    <slot />
+  </span>
+</template>