feat(#76): bound primary-route fetches and local-first driver summary

Add shared apiFetch timeouts/abort/typed errors with in-flight dedupe, a
RouteState UI for loading/empty/timeout/error+retry, and wire it through
Weekend (Data Health), Championship, Driver Profile, Briefing, Live, and
Race Hub. Driver summary is local-first with bounded optional OpenF1
enrichment so a hung remote call cannot block the profile.

Spike note: parseSourceMode defaults to openf1; driver summary now treats
omitted ?source= as auto so local season data is preferred.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/route-resilience.spec.ts

@@ -0,0 +1,42 @@
+import { test, expect } from '@playwright/test'
+
+test.describe('Primary-route resilience (forced errors)', () => {
+  test('Weekend leaves loading and shows retry after weekend-context failure', async ({
+    page,
+  }) => {
+    await page.route('**/api/v1/weekend-context', async (route) => {
+      await new Promise((r) => setTimeout(r, 50))
+      await route.fulfill({
+        status: 503,
+        contentType: 'application/json',
+        body: JSON.stringify({ error: 'forced weekend-context failure', stale: false }),
+      })
+    })
+
+    await page.goto('/')
+    await expect(page.getByTestId('weekend-error')).toBeVisible({ timeout: 15_000 })
+    await expect(page.getByRole('button', { name: 'Retry' })).toBeVisible()
+    await expect(page.getByTestId('weekend-error')).not.toHaveText(/API 503|forced weekend-context/i)
+  })
+
+  test('Driver Profile leaves loading and shows retry after summary timeout', async ({ page }) => {
+    await page.route('**/api/v1/driver/summary**', async (route) => {
+      // Hold the connection past the UI wait without fulfilling — the browser
+      // abort/timeout path is covered in unit tests; here we force an HTTP error
+      // so the shared RouteState recovery UI is exercised hermetically.
+      await route.fulfill({
+        status: 504,
+        contentType: 'application/json',
+        body: JSON.stringify({ error: 'forced timeout', stale: false }),
+      })
+    })
+    await page.route('**/api/v1/seasons', (route) =>
+      route.fulfill({ contentType: 'application/json', body: JSON.stringify([2025]) }),
+    )
+
+    await page.goto('/drivers/1?year=2025')
+    await expect(page.getByTestId('driver-profile-error')).toBeVisible({ timeout: 15_000 })
+    await expect(page.getByRole('button', { name: 'Retry' })).toBeVisible()
+    await expect(page.getByTestId('driver-profile-error')).not.toHaveText(/API 504/i)
+  })
+})