fix(ui): отображать одиночные измерения на графике трафика

tests/e2e/traffic-details.spec.ts

@@ -147,3 +147,31 @@ test('Итоги трафика: Sparkline сохраняет разрывы и
   await expect(page.getByLabel('Нет истории измерений')).toHaveCount(2)
   await expect(page.getByRole('img', { name: 'История измерений', exact: true })).toHaveCount(0)
 })
+
+test('История RX/TX: одиночные значения и ноль видны между пропусками', async ({ page }) => {
+  const control = await setup(page)
+  const history = page.getByRole('region', { name: 'История RX/TX' })
+  control.series = [0]
+  control.txSeries = []
+  await page.getByRole('button', { name: '24ч', exact: true }).click()
+  const dots = history.locator('circle[data-isolated-direction]')
+  await expect(dots).toHaveCount(1)
+  await expect(dots.first()).toBeVisible()
+  await expect(dots.first()).toHaveAttribute('data-isolated-direction', 'rx')
+  expect(await dots.first().getAttribute('cx')).not.toMatch(/NaN|Infinity/)
+  expect(await dots.first().getAttribute('cy')).not.toMatch(/NaN|Infinity/)
+  control.series = [2, null, 0, null, 3]
+  control.txSeries = [1, 2, 3, 4, 5]
+  await page.getByRole('button', { name: '15м', exact: true }).click()
+  await expect(history.locator('circle[data-isolated-direction="rx"]')).toHaveCount(3)
+  await expect(history.locator('circle[data-isolated-direction="tx"]')).toHaveCount(0)
+  const positions = await dots.evaluateAll(nodes => nodes.map(node => Number(node.getAttribute('cx'))))
+  expect(positions[0]).toBeLessThan(positions[1])
+  expect(positions[1]).toBeLessThan(positions[2])
+  await history.screenshot({ path: "test-results/traffic-isolated-points.png" })
+  control.series = [1, 2, 3]
+  control.txSeries = [0]
+  await page.getByRole('button', { name: '4ч', exact: true }).click()
+  await expect(history.locator('circle[data-isolated-direction="rx"]')).toHaveCount(0)
+  await expect(history.locator('circle[data-isolated-direction="tx"]')).toHaveCount(1)
+})