Add mr-timelog skill (GitLab time tracking from MR commits)
Adds the mr-timelog skill: drafts GitLab timelog entries from an MR's commits and posts them to the issues the MR closes, via GraphQL timelogCreate.
- Closing-issues-only target discovery (no branch/commit-name inference)
- Stateless date watermark from existing timelogs (no double-counting)
- Interactive (draft→approve→post) and unattended sweep modes
- Inline
glab, ships as a singleSKILL.md
Includes the design PRD under docs/prds/2026-06-03/. Validated end-to-end against a live MR.