## Stacked on #4284 — tests only
This PR contains **only the tests** that guard the production fixes in
#4284 (its base). Review #4284 first; this branch adds no production
code.
## What
Caller-driven replica-lag and idempotency guards for every fixed site:
- Each guard **drives the real exported caller** (route loader/action,
presenter `.call()`, service, or engine method) against a **real
Postgres** with the owning replica frozen via the shared
`laggingReplica` testcontainer primitive — never a store-seam
reimplementation.
- For a **fixed** site the guard goes **RED when the production change
is reverted**; for a **tolerated read-view** site it's a caller-driven
**GREEN** proof the miss self-heals (returns null/empty, no mutation,
row live on primary).
- The **global-scope idempotency** guard drives the real dedup + claim
path through a **real `MollifierBuffer` over a Redis testcontainer**
(real SETNX/poll/publish), and covers the cross-DB **andWait** waitpoint
wiring and the **expired/failed clear-and-recreate** reacquire cases.
Run with `vitest --no-file-parallelism` (testcontainers). Verified
GREEN, and revert→RED verified per fixed site.
Daniel Sutton
a7c734c223