docs: R-84 SHIPPED (agent v0.103.0) + demo-hp's first offsite backup

R-84 resolved by asking the STORAGE rather than persisting the store: ground
truth, so a pruned archive correctly stops counting where a persisted record
would keep claiming a backup that no longer exists. Proven live on both boxes
with the in-memory store cold.

demo-hp's FIRST EVER offsite backup landed (4.25 GB) — the R-82 finding closed
on the box where it was worst. Controller v0.175.0 deployed to both boxes.

CONTEXT.md

@@ -41,8 +41,12 @@ or retiring it is → **R-83**.
   the code path that consumes it, then escalated before finishing the check.
   **NOT done:** the offsite tier is never AUTOMATICALLY restore-tested (the scheduled test only ever
   selects the primary tier); the hub infers "PBS ⇒ weekly" from storage TYPE rather than a reported
-  cadence; every agent restart re-triggers an offsite backup (R-84). The installer-default fleet flip
-  waits on a full weekly cycle. Evidence: `audits/SPIKE-r82-phase0-2026-07-26.md`, `REPORT.md`.
+  cadence. The installer-default fleet flip waits on a full weekly cycle.
+  **R-84 SHIPPED (agent v0.103.0)** — the cold in-memory store no longer causes a redundant backup:
+  the due-check asks the STORAGE (ground truth) instead of persisting state, so a pruned archive
+  correctly stops counting. Proven live on both boxes with the store cold. **demo-hp's FIRST EVER
+  offsite backup landed** (4.25 GB) — the R-82 finding closed on the box where it was worst.
+  Controller v0.175.0 deployed to both boxes. Evidence: `audits/SPIKE-r82-phase0-2026-07-26.md`, `REPORT.md`.
 
 - **2026-07-26 — hub v0.75.0: R-81 SHIPPED — "no signal" is not "bad signal".** Third instance of
   one class (hub v0.12.0 `expected_backup_missed` daily-for-everyone; hub v0.73.0 `offsite_stale`