feat(explorer): mission-control resilience, ops token labels, and CI validate

Add SSE reconnect with backoff, fallback REST polling, visibility-aware refresh,
extended token-list labels on operations pages, validate-on-pr workflow, and smoke coverage.

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

scripts/e2e-sprint-smoke.spec.ts

@@ -25,4 +25,9 @@ test.describe('Explorer sprint smoke', () => {
     await page.goto(`${EXPLORER_URL}/tokens/${CANONICAL_CUSDT}`, { waitUntil: 'domcontentloaded', timeout: 20000 })
     await expect(page.getByText(/cUSDT|Tether/i).first()).toBeVisible({ timeout: 10000 })
   })
+
+  test('operations hub loads extended token list note', async ({ page }) => {
+    await page.goto(`${EXPLORER_URL}/operations`, { waitUntil: 'domcontentloaded', timeout: 20000 })
+    await expect(page.getByText(/Extended Metamask dual-chain catalog/i)).toBeVisible({ timeout: 10000 })
+  })
 })