Move round scheduler in-app via instrumentation.ts, remove cron endpoint

Round open/close scheduling now runs as a 60s setInterval inside the
app process (via instrumentation.ts register hook) instead of needing
an external crontab. Removed the /api/cron/round-scheduler endpoint.

- DRAFT rounds auto-activate when windowOpenAt arrives
- ACTIVE rounds auto-close when windowCloseAt passes
- Uses existing activateRound/closeRound from round-engine

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/server/services/round-scheduler.ts

@@ -0,0 +1,67 @@
+import { prisma } from '@/lib/prisma'
+import { activateRound, closeRound } from './round-engine'
+
+/**
+ * Check for rounds that need to be automatically opened or closed
+ * based on their windowOpenAt / windowCloseAt timestamps.
+ * Called on a 60-second interval from instrumentation.ts.
+ */
+export async function processScheduledRounds(): Promise<{
+  activated: number
+  closed: number
+}> {
+  const now = new Date()
+  let activated = 0
+  let closed = 0
+
+  // Find a SUPER_ADMIN to use as the actor for audit logging
+  const systemActor = await prisma.user.findFirst({
+    where: { role: 'SUPER_ADMIN' },
+    select: { id: true },
+  })
+
+  if (!systemActor) {
+    return { activated, closed }
+  }
+
+  // 1. Activate DRAFT rounds whose windowOpenAt has arrived
+  const roundsToOpen = await prisma.round.findMany({
+    where: {
+      status: 'ROUND_DRAFT',
+      windowOpenAt: { lte: now },
+      competition: { status: { not: 'ARCHIVED' } },
+    },
+    select: { id: true, name: true },
+  })
+
+  for (const round of roundsToOpen) {
+    const result = await activateRound(round.id, systemActor.id, prisma)
+    if (result.success) {
+      activated++
+      console.log(`[RoundScheduler] Activated round: ${round.name}`)
+    } else {
+      console.warn(`[RoundScheduler] Failed to activate "${round.name}":`, result.errors)
+    }
+  }
+
+  // 2. Close ACTIVE rounds whose windowCloseAt has passed
+  const roundsToClose = await prisma.round.findMany({
+    where: {
+      status: 'ROUND_ACTIVE',
+      windowCloseAt: { lte: now },
+    },
+    select: { id: true, name: true },
+  })
+
+  for (const round of roundsToClose) {
+    const result = await closeRound(round.id, systemActor.id, prisma)
+    if (result.success) {
+      closed++
+      console.log(`[RoundScheduler] Closed round: ${round.name}`)
+    } else {
+      console.warn(`[RoundScheduler] Failed to close "${round.name}":`, result.errors)
+    }
+  }
+
+  return { activated, closed }
+}