FN-7464: speed up insights route retry tests

Collapse deliberate retry waits in the insights route test suite while preserving retry coverage.

- Mock node:timers/promises in insights route tests so retry backoff resolves immediately.
- Document the FN-7464 performance rationale with an FNXC dashboard test comment.

Files changed:
 packages/dashboard/src/__tests__/insights-routes.test.ts | 12 ++++++++++++
 1 file changed, 12 insertions(+)

Fusion-Task-Id: FN-7464

Fusion-Task-Lineage: a4a77c7e-61ba-4abd-be80-059a2df55add

Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>

packages/dashboard/src/__tests__/insights-routes.test.ts

@@ -58,6 +58,18 @@ vi.mock("@fusion/engine", () => ({
   resolveMcpServersForStore: piMocks.resolveMcpServersForStore,
 }));
 
+/*
+FNXC:DashboardTests 2026-07-03-02:12:
+FN-7464 measured the only remaining slow test-body seam as retryable insight-route failures waiting the production 250ms retry delay from node:timers/promises. Keep route-boundary retry coverage and assertions intact, but collapse that deliberate backoff in this file so the suite does not spend real wall time on retry pacing.
+*/
+vi.mock("node:timers/promises", async () => {
+  const actual = await vi.importActual<typeof import("node:timers/promises")>("node:timers/promises");
+  return {
+    ...actual,
+    setTimeout: vi.fn(() => Promise.resolve()),
+  };
+});
+
 vi.mock("../project-store-resolver.js", async () => {
   const actual = await vi.importActual<typeof import("../project-store-resolver.js")>("../project-store-resolver.js");
   return {