fix: fall back to dirname/unknown when git context is absent

[collinstraka-clov]

Problem

gstack-review-log uses set -euo pipefail, which treats empty strings as unbound variables. When run outside a git repo (or in a repo with no remote configured), gstack-slug produces empty strings for SLUG and BRANCH, causing:

gstack-review-log: line 8: SLUG: unbound variable
gstack-review-log: line 9: BRANCH: unbound variable

This breaks any gstack review skill (e.g. /autoplan, /plan-ceo-review) when the working directory isn't a git repo with a remote.

Fix

Two changes in gstack-slug:

1. Add || true to the git commands so set -e doesn't abort when git context is missing
2. Fall back to basename "$PWD" for SLUG and "unknown" for BRANCH when the values are empty

Repro

Run any gstack review skill in a directory with no git remote configured.

🤖 Generated with Claude Code

[time-attack]

@16francej Please close this PR. Current main already handles missing Git context and includes stronger safe slug caching. This branch targets the old helper, so its useful idea has already been incorporated.

[capy-ai]

Thanks for this, @collinstraka-clov. The fix is now on main: bin/gstack-slug was rewritten with basename and username fallbacks (already on main as of v1.91.16.0). Closing as superseded; if you still see the problem on the latest gstack, please open an issue with ./setup --status output.