fix(test): use getByTestId for reliable fills in webkit

Replace page.fill('[data-testid=...]') with page.getByTestId().fill()
to fix webkit race condition where CSS selector fills didn't update
Svelte reactive state before assertions fired.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jaysin586

tests/default.test.ts

@@ -6,16 +6,16 @@ test.describe('SvelteDiffMatchPatch', () => {
     })
 
     test('renders a visible diff', async ({ page }) => {
-        await page.fill('[data-testid="text1"]', 'hello world')
-        await page.fill('[data-testid="text2"]', 'hello brave world')
+        await page.getByTestId('text1').fill('hello world')
+        await page.getByTestId('text2').fill('hello brave world')
         await expect(page.getByTestId('diff-result')).toContainText('brave')
         await expect(page.getByTestId('diff-result')).toContainText('hello')
         await expect(page.getByTestId('diff-result')).toContainText('world')
     })
 
     test('applies custom rendererClasses', async ({ page }) => {
-        await page.fill('[data-testid="text1"]', 'foo shoo')
-        await page.fill('[data-testid="text2"]', 'bar shoo')
+        await page.getByTestId('text1').fill('foo shoo')
+        await page.getByTestId('text2').fill('bar shoo')
         await expect(page.getByTestId('diff-result').locator('.diff-remove')).toBeVisible()
         await expect(page.getByTestId('diff-result').locator('.diff-insert')).toBeVisible()
         await expect(page.getByTestId('diff-result').locator('.diff-equal')).toBeVisible()

tests/snippets.test.ts

@@ -16,8 +16,8 @@ test.describe('SvelteDiffMatchPatch', () => {
     })
 
     test('applies custom rendererClasses', async ({ page }) => {
-        await page.fill('[data-testid="text1"]', 'foo shoo')
-        await page.fill('[data-testid="text2"]', 'bar shoo')
+        await page.getByTestId('text1').fill('foo shoo')
+        await page.getByTestId('text2').fill('bar shoo')
         await expect(page.getByTestId('diff-result').locator('.diff-remove')).toBeVisible()
         await expect(page.getByTestId('diff-result').locator('.diff-insert')).toBeVisible()
         await expect(page.getByTestId('diff-result').locator('.diff-equal')).toBeVisible()