The keyless fixture now carries the goal chain end to end, mirroring the
host: /goal enters the command catalog and its execute path brackets a
goal/change create with the command lifecycle pair; the six mutation verbs
CAS-check the projected current goal and append whole-value changes (the
shared append path broadcasts the session event and the goal projection
frame); the tail-page projections block and the mux-open baseline always
carry the goal key (null before create / after clear). Connection specs
follow: the lifecycle round-trip replaces the not-implemented stubs, and
the mux baseline expects the third unit frame.
Also: GoalBar inline errors use ASCII parens around the code (review
feedback on #842).