fix(insights): keep the assessment card polling while a stale text revalidates

The stale-while-revalidate path serves the last-good assessment on a cache
miss and returns a terminal payload, so the status hook stopped polling. The
worker warmed a fresh assessment out of band seconds later, but the open card
never picked it up — the stale text stuck until the page remounted.

Add a `revalidating` flag to the read-only miss outcome, set only when
last-good text is served AND a refresh was enqueued (false on the
suppressed-stub branch and when no prior text exists). Thread it through the
generic metric-status generator and the seven specialised generators onto the
wire, type it on the client, and make `nextStatusPollInterval` keep polling on
`preparing || revalidating`. The existing 12-attempt ceiling bounds both
signals, so a persistently failing generation still cannot poll forever.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
(cherry picked from commit c9217534fbdb304c4df1b6eb55fb19e4360b8a10)

src/hooks/__tests__/use-insight-status.test.ts

@@ -20,6 +20,9 @@ describe("nextStatusPollInterval — v1.8.4 poll ceiling", () => {
     // A terminal `no-provider` / settled payload never carries preparing,
     // so it stops immediately regardless of attempt count.
     expect(nextStatusPollInterval(false, 0)).toBe(false);
+    // A settled payload with neither preparing nor revalidating is terminal.
+    expect(nextStatusPollInterval(false, 0, false)).toBe(false);
+    expect(nextStatusPollInterval(undefined, 0, undefined)).toBe(false);
   });
 
   it("keeps polling while preparing and below the cap", () => {
@@ -42,4 +45,24 @@ describe("nextStatusPollInterval — v1.8.4 poll ceiling", () => {
     expect(interval).not.toBe(false);
     expect(interval as number).toBeGreaterThan(0);
   });
+
+  // v1.9.0 — stale-while-revalidate: a terminal payload that serves last-good
+  // text sets `revalidating` so the open card keeps polling until the
+  // freshly-warmed assessment lands, without a remount.
+  it("keeps polling on revalidating even when not preparing", () => {
+    expect(nextStatusPollInterval(false, 0, true)).toBeTypeOf("number");
+    expect(nextStatusPollInterval(undefined, 1, true)).toBeTypeOf("number");
+    expect(
+      nextStatusPollInterval(false, STATUS_POLL_MAX_ATTEMPTS - 1, true),
+    ).toBeTypeOf("number");
+  });
+
+  it("honours the same attempt cap for revalidating", () => {
+    expect(
+      nextStatusPollInterval(false, STATUS_POLL_MAX_ATTEMPTS, true),
+    ).toBe(false);
+    expect(
+      nextStatusPollInterval(false, STATUS_POLL_MAX_ATTEMPTS + 5, true),
+    ).toBe(false);
+  });
 });