Adds a new subcommand that re-detects gbrain installation state and
persists the result to ~/.gstack/gbrain-detection.json. The detection
file is consumed by gen-skill-docs --respect-detection (next commit)
to decide whether to render the GBRAIN_CONTEXT_LOAD and
GBRAIN_SAVE_RESULTS resolver blocks in user-local SKILL.md generation.
Reuses the existing bin/gstack-gbrain-detect helper for the actual
probe; this subcommand just persists + summarizes. Users run it after
installing or uninstalling gbrain so their locally generated SKILL.md
files match their installation state.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
7939269bae