fix(health): re-run integrity check on Refresh health, not just re-read cache

The dashboard's corruption banner refresh action was a no-op for clearing
stale corruption flags after the user repaired the DB. Database.
scheduleBackgroundIntegrityCheck runs the integrity check exactly once at
engine boot and then early-returns forever after, so corruptionDetected
was sticky for the life of the process. POST /api/health/refresh just
read the cached flag back.

Add Database.refreshIntegrityCheck() and TaskStore.refreshDatabaseHealth()
which synchronously re-run the integrity check and update the cached
state, and have the route use them. After REINDEX / fn db --vacuum / any
in-place repair, users can now clear the banner without restarting the
engine.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/src/server.ts

@@ -1329,7 +1329,7 @@ export function createServer(store: TaskStore, options?: ServerOptions): ReturnT
 
   app.post("/api/health/refresh", (_req, res) => {
     const report = store.refreshTaskIdIntegrityReport();
-    const database = store.getDatabaseHealth();
+    const database = store.refreshDatabaseHealth();
     res.json({
       status: !database.healthy || database.corruptionDetected || report.status === "anomaly" ? "degraded" : "ok",
       version: cliPackageVersion,