fix(FN-branch-group): address PR review feedback (#1357)
- abandon route: guard already-abandoned groups (matches CLI)
- CLI branch-group list: single task fetch via filterTasksByBranchGroup (N+1)
- branch-name validator: git check-ref-format parity (//, dot-segments, .lock, @, @{, trailing /.)
- updateBranchGroup: validate renamed branchName too
- already-merged-detector: escape regex metachars in git log --grep; non-vacuous prose-mention assertion
- group PR callbacks: thread per-project cwd through SyncGroupPrFn/reconcile/github helpers (multi-project correctness)
- merger: group-PR sync is fire-and-forget (never blocks merge completion); deterministic test handle
- coordinator: sibling PR reuse only when open; reconcile skips member fetch on read-only path; argv-based git calls (no shell)
- task-lifecycle: legacy group-PR path links open PRs only; branch probes via execFile argv (injection hardening)
- mission/planning: branchContext.groupId only stamped for actual shared-mode members (groupId now optional)
- UI: Abandon reachable whenever PR is open (decoupled from completion); promote stays completion-gated
- tests: deterministic concurrency gate, real reconcile path in e2e, Surface Enumeration sections
f3bc757d22