The QueueKind enum has graceful_stop, start, and stop variants but the
dashboard QUEUE_KIND_GLYPH map only covered rebuild/meta_update/spawn/
destroy/restart/startup_sweep/perm_change — the three missing kinds
rendered as '?' in the build queue UI.
This became visible with the deferred start-after-rebuild change: a fast-lane
Start entry now appears as a child of its Rebuild parent, but showed the
fallback '?' glyph.
Glyphs assigned: graceful_stop=⏹, start=▶, stop=■.
Also update the dashboard.md kind-glyph list to include all nine kinds and
note that deferred start-after-rebuild entries also use parent_id grouping.
688531030b