chore(cron): move recommendation + LLM enrichment to overnight

DeepSeek API spend isn't justified by minute-by-minute freshness when
ops review insights in the morning. Run rules at 02:00 UTC and the
enrichment pass at 03:00 UTC so summaries are ready by 9 AM local.

- RecommendationsRunWorker: hourly → 02:00 UTC daily
- InsightLlmEnrichmentWorker: every 5 min → 03:00 UTC daily

config/runtime.exs

@@ -258,10 +258,14 @@ if config_env() == :prod do
          {"*/5 * * * *", Towerops.Workers.SystemInsightWorker},
          # Wireless client health insights every 5 minutes
          {"*/5 * * * *", Towerops.Workers.WirelessInsightWorker},
-         # Enrich active insights with LLM-generated summaries every 5 minutes
-         {"*/5 * * * *", Towerops.Workers.InsightLlmEnrichmentWorker},
-         # Run multi-source recommendation rules hourly
-         {"0 * * * *", Towerops.Workers.RecommendationsRunWorker},
+         # Run multi-source recommendation rules nightly at 02:00 UTC.
+         # Fresh insights are ready before the LLM enrichment pass at 03:00.
+         {"0 2 * * *", Towerops.Workers.RecommendationsRunWorker},
+         # Enrich active insights with LLM-generated summaries nightly at
+         # 03:00 UTC. Batched once a day instead of every 5 minutes — the
+         # API spend isn't justified by minute-by-minute freshness when
+         # ops review the dashboard in the morning.
+         {"0 3 * * *", Towerops.Workers.InsightLlmEnrichmentWorker},
          # Gaiia reconciliation insights nightly at 4:30 AM
          {"30 4 * * *", Towerops.Workers.GaiiaInsightWorker},
          # Backhaul capacity utilization insights every 15 minutes