docs(cluster): self-first seed ordering replaces the self-form fallback

docs/Redundancy.md's bootstrap section is rewritten around the mechanism that is
actually in force: which of Akka's two bootstrap processes runs is decided by
whether seed-nodes[0] is this node's own address, so the ORDER of Cluster:SeedNodes
is the fix, not a timer. Adds the per-process table, the shipped self-first
example, why the validator is conditional (site nodes are not seeds) and why it
matches PublicHostname rather than the 0.0.0.0 bind address.

The retirement is documented rather than erased: a new subsection explains that a
watchdog outside the join handshake cannot tell "no seed answered" from "a seed
answered and the join is in flight", and the ea45ace1 live-gate finding is kept
verbatim as the evidence that produced that conclusion (InitJoinAck at 10:49:05,
old incarnation retired 10:49:06, watchdog fired 10:49:15, second cluster). The
watchdog's own earlier PASS is kept too — it did pass what it was gated on.

Also: a live gate for the NEW mechanism is registered as outstanding (not
re-drilled on the docker-dev rig since the swap), and the plan doc that shipped
the watchdog gets a superseded banner rather than an edit, so the execution record
and its Task 8 finding stay readable.

Ripple: CLAUDE.md cluster section, docs/Configuration.md + docs/v2/Cluster.md +
docs/ServiceHosting.md SeedNodes entries, the per-cluster-mesh design doc's two
"CLOSED by SelfFormAfter" notes, and mesh-program Phase 6 (which had this
convergence queued — now marked done early) + Phase 7's live-gate name.

docs/plans/2026-07-22-per-cluster-mesh-program.md.tasks.json

@@ -9,7 +9,7 @@
     {"id": 4, "subject": "Phase 4: cut driver-side ConfigDb — EfAlarmConditionStateStore to LocalDb, DbHealthProbeActor ServiceLevel input, OpcUaPublishActor audit (live gate)", "status": "pending", "blockedBy": [3]},
     {"id": 5, "subject": "Phase 5: gRPC oneof stream contract; migrate 7 observability topics; AdminUI reconnect story", "status": "pending", "blockedBy": [2]},
     {"id": 6, "subject": "Phase 6: mesh partition — per-pair seeds, cluster-scoped roles/singletons, co-location rig rewrite, secrets replication re-scope", "status": "pending", "blockedBy": [0, 4, 5]},
-    {"id": 7, "subject": "Phase 7: failover drill per pair (incl. shared-VM failure) + close auto-down 1v1 and SelfFormAfter live gates + operator runbook", "status": "pending", "blockedBy": [6]}
+    {"id": 7, "subject": "Phase 7: failover drill per pair (incl. shared-VM failure) + close auto-down 1v1 and self-first cold-start-alone live gates + operator runbook", "status": "pending", "blockedBy": [6]}
   ],
   "lastUpdated": "2026-07-22T00:00:00Z"
 }