fix(withings): keep the sleep nights read around a failing one

One failing per-night stage read threw out of the loop, so the nights
already read and the summary vitals were never written. A failed read
now leaves the others to be written, books the leg failed afterwards
and marks the night to be read first next run. A night that answers
without a stage three times is no longer read on every run; a full sync
still reads it. The per-night record lives on the connection (migration
0421) and is reset on reconnect.

src/app/api/withings/callback/route.ts

@@ -216,6 +216,9 @@ export const GET = apiHandler(async (request: NextRequest) => {
           // A reconnect may come with another developer app (another plan), so
           // what the old grant's plan refused is asked for again.
           apiPlanState: Prisma.DbNull,
+          // A reconnect may be another account or device, so nights it gave
+          // up on are tried again.
+          sleepStageReads: Prisma.DbNull,
         },
         create: {
           userId: user.id,