feat: Conductor renders AskUserQuestion decisions as prose by default

In Conductor, native AskUserQuestion is disabled and the MCP variant is
flaky, so skills now render every decision as a plain-text prose brief the
user answers by typing a letter — proactively, not as a failure reaction.

- Preamble emits CONDUCTOR_SESSION, gated on != headless so eval/CI inside
  Conductor still BLOCKs instead of rendering prose to nobody.
- AskUserQuestion Format gains a Conductor-default-prose rule (auto-decide
  preferences still apply first; prose decisions log via gstack-question-log
  since PostToolUse never fires), a one-way/destructive typed-confirmation
  rule, and a typed-reply continuation protocol for split chains.
- Regenerated all SKILL.md + ship golden fixtures; bumped affected carve
  skeleton caps to absorb the always-loaded additions.

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

benchmark/SKILL.md

@@ -51,6 +51,13 @@ echo "REPO_MODE: $REPO_MODE"
 _SESSION_KIND=$(~/.claude/skills/gstack/bin/gstack-session-kind 2>/dev/null || echo "interactive")
 case "$_SESSION_KIND" in spawned|headless|interactive) ;; *) _SESSION_KIND="interactive" ;; esac
 echo "SESSION_KIND: $_SESSION_KIND"
+# Conductor host: AskUserQuestion is unreliable here (native disabled, MCP
+# variant flaky), so skills render decisions as prose instead of calling the
+# tool. Gated on !headless so an eval/CI run INSIDE Conductor (GSTACK_HEADLESS)
+# still BLOCKs rather than rendering prose to nobody.
+if [ "$_SESSION_KIND" != "headless" ] && { [ -n "${CONDUCTOR_WORKSPACE_PATH:-}" ] || [ -n "${CONDUCTOR_PORT:-}" ]; }; then
+  echo "CONDUCTOR_SESSION: true"
+fi
 _LAKE_SEEN=$([ -f ~/.gstack/.completeness-intro-seen ] && echo "yes" || echo "no")
 echo "LAKE_INTRO: $_LAKE_SEEN"
 _TEL=$(~/.claude/skills/gstack/bin/gstack-config get telemetry 2>/dev/null || true)