fix(server): update branch labels after terminal checkouts#23422

fix(server): HEAD watch failures log bounded diagnostics instead of the raw cause

fix(server): a HEAD watch that ended restarts for the next subscriber

fix(server): a checkout read blocked by index.lock retries until it succeeds

docs(server): explain HEAD watcher tracing lifetime

fix(fixtures): clear inherited Git repository environment

fix(server): a failed local status read no longer leaves stale Changes totals

fix(server): checked-out branch matches status when a same-named tag exists

Merge remote-tracking branch 'origin/main' into fix/issue-7409

fix(server): keep branch status coherent during terminal checkouts

test(server): add synthetic checkout evidence fixtures

Merge origin/main into fix/issue-7409

fix(server): a branch checked out in the terminal updates the branch label right away

test(server): reproduce issue 7409 terminal checkout leaves branch label stale