v1.4.37.1 — event-loop unblock on the read path

Hotfix on top of v1.4.37. The post-deploy verify caught
/api/analytics cold-mount hits of ~62 s and parallel /api/health
checks of ~58 s on the live instance, far above the v1.4.37
1.5-3 s perf claim. Root cause: the synchronous
ensureUserRollupsFresh(userId) call at the top of each heavy
read path folds the trailing 90-day DAY window when the rollup
watermark trails the newest measurement. On a power-user account
whose iOS step samples push the watermark every few minutes,
each cache miss synchronously paid the full refresh cost on a
Node worker that also serves the rest of the request fan-out
(including /api/health, /api/version, and concurrent iOS calls),
and the event loop was blocked for the duration of the
recompute.

Convert the three call sites (analytics route, comprehensive
aggregator, summaries slice) to fire-and-forget. The downstream
probeRollupCoverage gate falls back to live SQL on partial
coverage so correctness is preserved; the only user-observable
change is one cache window of staleness on the very first
request after a new measurement landed.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "healthlog",
-  "version": "1.4.37",
+  "version": "1.4.37.1",
   "description": "Self-hosted personal-health-tracking PWA with Withings integration, AI insights, and doctor-report PDF export.",
   "license": "AGPL-3.0-only",
   "homepage": "https://healthlog.dev",