chore: bump v1.12.3.0 references to v1.15.1.0 to match merged-with-main release

Internal-only renames after merging origin/main bumped this branch's release
target from v1.12.3.0 → v1.15.1.0:

- gstack-upgrade/migrations/v1.12.3.0.sh → v1.15.1.0.sh (rename + log-prefix
  bump from "[v1.12.3.0]" to "[v1.15.1.0]")
- bin/gstack-brain-consumer header: "DEPRECATED in v1.12.3.0" → "DEPRECATED in
  v1.15.1.0"; removal target bumped from v1.13.0.0 → v1.16.0.0 (next minor
  after v1.15.1.0).
- bin/gstack-brain-uninstall: "no longer written ... since v1.12.3.0" →
  "since v1.15.1.0".

No behavior change. Test suite still 16/16 passing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

bin/gstack-brain-consumer

@@ -1,10 +1,10 @@
 #!/usr/bin/env bash
 # gstack-brain-consumer — manage the consumer (reader) registry.
 #
-# DEPRECATED in v1.12.3.0. This binary targets a gbrain HTTP /ingest-repo
+# DEPRECATED in v1.15.1.0. This binary targets a gbrain HTTP /ingest-repo
 # endpoint that never shipped on the gbrain side. Live federation now uses
 # `gbrain sources` directly via bin/gstack-gbrain-source-wireup. This file
-# stays for one cycle to avoid breaking external scripts; removal in v1.13.0.0.
+# stays for one cycle to avoid breaking external scripts; removal in v1.16.0.0.
 #
 # Consumer = a reader that ingests the gstack-brain git repo as a source of
 # session memory. v1 primary consumer is GBrain; later versions can register

bin/gstack-brain-uninstall

@@ -129,7 +129,7 @@ if [ -x "$WIREUP_BIN" ]; then
   "$WIREUP_BIN" --uninstall 2>/dev/null || true
 fi
 
-# ---- legacy consumers.json (no longer written by gstack-brain-init since v1.12.3.0) ----
+# ---- legacy consumers.json (no longer written by gstack-brain-init since v1.15.1.0) ----
 rm -f "$GSTACK_HOME/consumers.json" 2>/dev/null || true
 
 # ---- clear config keys ----

gstack-upgrade/migrations/v1.15.1.0.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
-# Migration: v1.12.3.0 — Wire existing brain-sync repos as gbrain federated sources
+# Migration: v1.15.1.0 — Wire existing brain-sync repos as gbrain federated sources
 #
-# Pre-1.12.3.0 /setup-gbrain wrote ~/.gstack/consumers.json with a placeholder
+# Pre-1.15.1.0 /setup-gbrain wrote ~/.gstack/consumers.json with a placeholder
 # `status: "pending"` and an empty `ingest_url`, expecting a gbrain HTTP
 # /ingest-repo endpoint that never shipped. This migration runs the real
 # wireup (gbrain sources add + worktree + initial sync) for users who
@@ -17,7 +17,7 @@
 set -euo pipefail
 
 if [ -z "${HOME:-}" ]; then
-  echo "  [v1.12.3.0] HOME is unset or empty — skipping migration." >&2
+  echo "  [v1.15.1.0] HOME is unset or empty — skipping migration." >&2
   exit 0
 fi
 
@@ -42,13 +42,13 @@ fi
 
 # Skip if helper missing (defensive — should always be present post-upgrade).
 if [ ! -x "$WIREUP_BIN" ]; then
-  echo "  [v1.12.3.0] $WIREUP_BIN missing or non-executable — skipping wireup." >&2
+  echo "  [v1.15.1.0] $WIREUP_BIN missing or non-executable — skipping wireup." >&2
   exit 0
 fi
 
-echo "  [v1.12.3.0] Wiring brain-sync repo into gbrain (federated source + initial sync)..."
+echo "  [v1.15.1.0] Wiring brain-sync repo into gbrain (federated source + initial sync)..."
 
 # No --strict: missing/old gbrain is a benign skip during a batch upgrade.
 "$WIREUP_BIN" || {
-  echo "  [v1.12.3.0] Wireup exited non-zero — re-run manually with: $WIREUP_BIN" >&2
+  echo "  [v1.15.1.0] Wireup exited non-zero — re-run manually with: $WIREUP_BIN" >&2
 }