`task start --repo .` failed with "cannot resolve base_ref 'HEAD'": the
server resolved the relative path against its own cwd. The CLI now makes
--repo and --path absolute before sending them, and the server rejects a
relative repo with BAD_PARAMS, as it already did for path.

A worker that ran `signaltty report` right away got NO_SUCH_TASK: the
task entered the store only after its pane had spawned. It is now
committed before the spawn and gets its pane id afterwards; a spawn
failure fails the stored task as before. The response carries the stored
task, so an early report is not overwritten.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>