docs: add parity prep templates for vuln and scheduler

docs/db/reports/scheduler-mongo-request-20251208.md

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+# Scheduler Mongo Snapshot Request · 2025-12-08
+
+**To:** DevOps Guild, Scheduler Guild
+
+**Context:** Scheduler Postgres cutover (Sprint 3402 · PG-T2.9–T2.11) is blocked awaiting Mongo data for backfill/parity. Target dates: snapshot/approval by 2025-12-12; parity run/report by 2025-12-14.
+
+## Request
+1) Provide a MongoDB snapshot (or live read-only connection string) for Scheduler collections covering jobs/triggers/leases/history/metrics.
+2) Confirm whether backfill is required or if a start-clean posture is approved for staging/production.
+3) If snapshot is provided, include:
+   - Connection string or dump location
+   - Snapshot timestamp
+   - List of collections included
+   - Expected row counts by collection
+
+## Delivery
+- Drop details in this file (or reply in the sprint log) and set Action #1 in `SPRINT_3402_0001_0001_postgres_scheduler.md` to DONE.
+
+## Notes
+- Backfill tool: `Scheduler.Backfill` CLI (see sprint doc).
+- Parity report target: `docs/db/reports/scheduler-parity-20251214.md`.
+- Config to flip post-parity: `Persistence:Scheduler=Postgres`.
+