feat(FN-4760): complete Step 7 — document PR checks endpoint

Fusion-Task-Id: FN-4760
Fusion-Task-Lineage: 71db4a53-ee59-49f0-a1f7-232954b86660

.changeset/fn-4760-pr-checks-stream.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": minor
+---
+
+Add live PR check streaming in the dashboard PR panel, including failing-check surfacing with direct GitHub details links, and introduce `GET /api/tasks/:id/pr/checks` for all check runs with required-check rollup status.

docs/architecture.md

@@ -1573,6 +1573,15 @@ The GitHub tracking state listener now attaches to every registered project stor
 - Dashboard GitHub APIs + webhook route in `routes.ts`
 - Badge snapshots are streamed via `/api/ws` and `useBadgeWebSocket.ts`
 
+#### PR checks API
+- `GET /api/tasks/:id/pr/checks` returns live PR check data for the task PR:
+  - `checks: PrCheckStatus[]` (required and non-required checks)
+  - `rollup: "success" | "pending" | "failure" | "unknown"` derived from **required checks only** (merge-readiness semantics)
+  - `lastCheckedAt: string` timestamp for the fetch
+- Route behavior matches PR refresh safeguards:
+  - `404` when the task has no associated PR
+  - `429` when `githubRateLimiter` denies the repo request window, including `retryAfter`/`resetAt` details
+
 ---
 
 ## 14) Key Design Decisions