docs(vpn): dev recovered the minute prod left the shared PIA server

Closes the loop on the collision entry with the recovery evidence rather than
leaving it as an open question for the operator: dev's last Inactivity timeout is
23:05:06 UTC — the minute prod switched to .135 — and at 23:12:03 that same
session was still the live one, seven minutes unbroken against a two-minute
cycle, 4/4 ping replies at 146 ms, 0% loss, and vpn-class pod egress back to
158.173.241.36 on three consecutive probes.

Co-Authored-By: Claude Opus 5 <[email protected]>

platform/vpn-egress/README.md

@@ -68,6 +68,10 @@ Each reconnect steals `10.72.192.7` on that server; the loser receives nothing,
 off — every ~2 minutes, indefinitely. Neither environment had reliable vpn-class egress; prod's
 first probes looked green only because they landed inside an up-window.
 
+Dev recovered the minute prod left `.112`: its last `Inactivity timeout` is 23:05:06 UTC, and at
+23:12:03 that same session was still up — seven minutes unbroken against a two-minute cycle — with
+a source-bound ping returning 4/4 at 146 ms and vpn-class pod egress back to `158.173.241.36`.
+
 **Fix:** `vpn_egress_gateway_pia_remote` in `group_vars/vpn_egress_gateway_prod/vars.yml`
 rewrites just the `remote` line, pointing prod at `158.173.241.135` — another member of the
 same PIA Stockholm LB pool (`sweden.privacy.network` resolves to