refactor: Replace Rollup with Vite (#2656)

This is a high risk change: every byte the card ships is emitted by a
different bundler, minified by a different minifier, and every
stylesheet is compiled by a different sass. The intent is that the
card's behaviour is unchanged.

**Significant development win**: Build time drops from 24s to 1.1s 🎉 

Also adds a test suite ('dist') that runs against the built bundle.

tests/card-controller/style-manager.browser.test.ts

@@ -0,0 +1,44 @@
+import { describe, expect, it } from 'vitest';
+
+import { MountedCardFactory } from '../browser/mounted-card';
+import {
+  createStillCameraHASS,
+  createStillImageCardConfig,
+} from '../browser/test-utils';
+
+// A colour the dark theme sets and the card carries no other way. Reading it
+// back proves the stylesheet reached the card rather than merely compiling.
+// See src/scss/themes/dark.scss .
+const DARK_PRIMARY_BACKGROUND = '#111111';
+
+const mountThemed = async (themes: string[]) =>
+  await MountedCardFactory.createFromSource(
+    createStillImageCardConfig({ view: { theme: { themes } } }),
+    createStillCameraHASS(),
+  );
+
+describe('themes', () => {
+  it('should style the card from the theme it is configured with', async () => {
+    const card = await mountThemed(['dark']);
+    await card.waitForRender(
+      () => card.card.getAttribute('themes'),
+      'the card being given its themes',
+    );
+
+    expect(
+      getComputedStyle(card.card).getPropertyValue('--primary-background-color').trim(),
+    ).toBe(DARK_PRIMARY_BACKGROUND);
+  });
+
+  it('should not style the card from a theme it is not configured with', async () => {
+    const card = await mountThemed(['light']);
+    await card.waitForRender(
+      () => card.card.getAttribute('themes'),
+      'the card being given its themes',
+    );
+
+    expect(
+      getComputedStyle(card.card).getPropertyValue('--primary-background-color').trim(),
+    ).not.toBe(DARK_PRIMARY_BACKGROUND);
+  });
+});