feat(wipes): wire the auto-wiper — scheduled wipes now actually fire

wipe_schedules rows existed but nothing read or fired them — an operator could
set a wipe schedule and it would never trigger (the headline auto-wipe feature
was inert; the manual trigger worked, the scheduler did not).

- WipesService now implements OnModuleInit/OnModuleDestroy with a 60s executor
  (mirrors SchedulesService): bootstraps next_scheduled_run, then fires every
  active schedule whose next_scheduled_run <= now via triggerWipe(...'scheduled')
  -> instancesService.wipeForLicense -> the agent wipe handler, advancing
  next_scheduled_run from the cron each cycle (advances even on failure so a
  broken schedule can't re-fire every 60s).
- triggerWipe parameterized with triggerType ('manual' | 'scheduled') so
  wipe_history records the real origin.
- Extracted nextCronDate into src/common/cron.util.ts (shared by the event and
  wipe schedulers; was duplicated/private). Cron is evaluated UTC — the per-
  schedule timezone column is still not honored, a known limitation shared by
  both schedulers (follow-up: tz-aware cron lib).

Backend tsc green. Scheduling logic is at parity with the in-production event
scheduler; live end-to-end (a scheduled wipe deleting real files) verifies when
a game stack + agent are connected.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend-nest/src/common/cron.util.ts

@@ -0,0 +1,51 @@
+/**
+ * Minimal 5-field cron "next run" calculator, shared by the event scheduler
+ * (SchedulesService) and the wipe scheduler (WipesService).
+ *
+ * Supports `*` and exact numeric fields (minute hour day-of-month month
+ * day-of-week). Walks minute-by-minute up to 366 days ahead. Returns null on a
+ * malformed expression or if no match is found within a year.
+ *
+ * NOTE: the expression is evaluated in **UTC**. A per-schedule `timezone`
+ * column exists on both schedule tables but is NOT yet honored here — fixing it
+ * properly needs a timezone-aware cron library; tracked as a shared follow-up.
+ */
+export function nextCronDate(expr: string, after: Date): Date | null {
+  const parts = expr.trim().split(/\s+/);
+  if (parts.length !== 5) return null;
+
+  const [minuteExpr, hourExpr, domExpr, monthExpr, dowExpr] = parts;
+
+  const matches = (e: string, value: number): boolean => {
+    if (e === '*') return true;
+    return parseInt(e, 10) === value;
+  };
+
+  // Walk minute-by-minute up to 366 days forward to find the next match.
+  const candidate = new Date(after.getTime() + 60_000); // advance at least 1 minute
+  candidate.setSeconds(0, 0);
+
+  const limit = new Date(after.getTime() + 366 * 24 * 60 * 60 * 1000);
+
+  while (candidate < limit) {
+    const min = candidate.getUTCMinutes();
+    const hour = candidate.getUTCHours();
+    const dom = candidate.getUTCDate();
+    const month = candidate.getUTCMonth() + 1; // 1-12
+    const dow = candidate.getUTCDay(); // 0=Sun
+
+    if (
+      matches(minuteExpr, min) &&
+      matches(hourExpr, hour) &&
+      matches(domExpr, dom) &&
+      matches(monthExpr, month) &&
+      matches(dowExpr, dow)
+    ) {
+      return candidate;
+    }
+
+    candidate.setTime(candidate.getTime() + 60_000);
+  }
+
+  return null;
+}