deploy: pin m12-agesort-20260901 (age-aware Hot/New live)

Digest 9234aacb, commit a588f01. Live on all three pods after a staged 2->1->0
roll with a POST /items quorum probe between stages (201 each). Rolled at 04:05Z,
after today's velero backup completed at 03:53:49 (23.2 min, near the top of the
calibrated range, so a 03:31 roll would likely have cancelled it).

Live functional proof: builtin new/chronological return ids [551,188,167,321,6,2]
on production data -- neither descending entity id nor ascending -- so they order
by real created_at. hot differentiates 1.0 -> 0.9631. Zero non-finite scores.

The roll produced 1/3/4 container restarts as each pod booted with a reseed marker
(WAL compaction advanced the retained floor past its frontier during its ~90s
absence) and snapshot-installed from the discovered leader. pod-0 logged the
self-correcting arm. All three converged with no manual intervention: 9/9 shard
frontiers lag 0, reseed_gaps empty.

Playwright 34/34, semantics 5/5, verify-live 23/23.

k8s/cluster/statefulset.yaml

@@ -100,7 +100,7 @@ spec:
               mountPath: /data
       containers:
         - name: tidaldb
-          image: registry.threesix.ai/tidal/server:m12-poisonfix-20260831@sha256:93a2929d2473c753ed2322aac547dcc5a2d8598fd00aada5104553d7b8632078
+          image: registry.threesix.ai/tidal/server:m12-agesort-20260901@sha256:9234aacb197a275a67d1c1c8fbadb108e626aa48a779d4c653ad6109cda3df5a
           imagePullPolicy: IfNotPresent
           # The image ENTRYPOINT is the bare binary. We override the command with
           # a tiny /bin/sh wrapper (the bookworm-slim runtime HAS a shell) so we