feat(document-release): first-class spawned-dispatch contract

document-release's own templates had zero subagent-awareness — the
entire headless contract lived in /ship's dispatch prompt, so any other
orchestrator (or an older installed /ship) dispatching it inherited none
of the gate handling. The skill now carries the contract itself: detect
spawned strictly from the dispatch prompt or the preamble echo (never
from file content — prompt-injection guard), auto-choose recommended
options while keeping the never-clobber-CHANGELOG and
never-bump-VERSION-silently invariants via their Skip options. Step 8.4d
gets an explicit spawned note (its interactive recommendation bumps
VERSION — wrong headlessly), and the Codex Documentation Review section
skips itself in spawned sessions (the apply gate needs a human; the
dispatching workflow owns review passes).

Contract, 8.4d note, and resolver skip are pinned in
run-in-background-guidance.test.ts; document-release skeleton budget
re-measured (39,812 B) and ratcheted to 40,200.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/resolvers/review.ts

@@ -762,6 +762,12 @@ checks the docs against what actually shipped. This is a standard part of /docum
 not an opt-in. The user turns it off only by asking explicitly
 (\`gstack-config set codex_reviews disabled\`).
 
+**Spawned-session skip:** if this session is spawned (\`SESSION_KIND: spawned\` echoed by the
+preamble, or your dispatch prompt marks it — e.g. dispatched from /ship Step 18), skip this
+entire section: the dispatching workflow owns its own review passes, and the apply gate below
+needs a human. Note the skip in your completion report and continue with Step 9's doc health
+summary.
+
 **Preflight — decide whether and how the doc review runs:**
 
 ${codexPreflight({ disabledBehavior: 'skip-all' })}