New bin/gstack-builder-profile reads ~/.gstack/builder-profile.jsonl and
outputs structured summary (tier, signals, resources, topics). Single
source of truth for all closing state — no separate config keys or logs.
Uses bun-based JSONL parsing pattern from gstack-learnings-search.
Graceful fallback to introduction tier if bun unavailable or file missing.
26 unit tests covering tier computation, signal accumulation, cross-project
detection, nudge eligibility, resource dedup, and malformed JSONL handling.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Garry Tan