feat: wire setup-gbrain + brain-restore + brain-uninstall to use the helper

setup-gbrain Step 7 now invokes gstack-gbrain-source-wireup --strict after
gstack-brain-init + gbrain_sync_mode is set. Strict mode means the user sees
the failure rather than silently ending up with an unwired brain.

bin/gstack-brain-init drops 60 lines of dead code: the HTTP POST to
${GBRAIN_URL}/ingest-repo, the GBRAIN_URL_VAL/GBRAIN_TOKEN_VAL probes, the
consumers.json writer, and the chore commit step. CONSUMERS_FILE variable
declaration removed. The closing message no longer points at the dead
gstack-brain-consumer add path.

bin/gstack-brain-restore drops the 18-line consumers.json token-rehydration
block (was a no-op for the only consumer that ever existed). Adds a
best-effort wireup invocation after the brain-repo clone so 2nd-Mac restore
gets gbrain federation automatically. Failure prints a stderr WARNING but
does not abort the restore — restore's primary job is the git clone.

bin/gstack-brain-uninstall calls the helper's --uninstall mode (which
removes the gbrain source registration, the git worktree, and the
future-launchd-plist stub) before the existing legacy consumers.json
removal. Ordering is fragile-by-design: helper derives source-id via
multi-fallback so it works even after .git is destroyed.

bin/gstack-brain-consumer gets a DEPRECATED header note. Stays in the tree
for one cycle of grace; removal in v1.13.0.0.

setup-gbrain/SKILL.md is regenerated from the .tmpl via gen:skill-docs.

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

bin/gstack-brain-consumer

@@ -1,6 +1,11 @@
 #!/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
+# 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.
+#
 # 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
 # Codex, OpenClaw, or third-party readers.