Feat: repo-sync skill (promote from standing order)

[rubambiza]

Companion to the RepoMan epic rossoctl/automation#72. Implemented as part of Phase 4 (rossoctl/automation#75); do not start until that phase begins.

Problem

repo-sync exists today only as a standing order (standing-orders/repo-sync.md), not a first-class skill. RepoMan needs it as a real skill for (a) the OpenClaw skill-install path where the agent loads the skill from a local clone, and (b) RepoMan setup step 4 offering the sync option with a clear skill description. (Original ask: open issue B in the RepoMan spec.)

Scope

• New skill skills/repo-sync/ (SKILL.md + scripts) in this repo.
• Input: repos.json -> [{owner, name}, ...], plus refreshing ~/agent-skills/ itself on OpenClaw.
• Action: clone if missing, git pull if present, per repo. Clone target is owner-namespaced <repos_dir>/<owner>/<name>/.
• Read-only toward GitHub: failed repos are logged, not fatal; nothing posted.

Note on branch hygiene

The branch-safety behavior (restore a clone to its main branch before syncing when the tree is clean) is tracked separately as rossoctl/automation#80 (v0.1.1). This issue is the skill's creation; #80 hardens its sync behavior afterward.

Sequencing

Paired with Phase 4 (rossoctl/automation#75), which updates automation/scripts/repo-sync.sh for repos.json input and the owner-namespaced clone target.

Assisted-By: Claude Code