Closes#415. Server-derived health object on the channel list + detail DTOs (built-timeline detection, kind-agnostic across all 5 PlayoutScheduleKind; assessable gate keyed to the owning channel's mode), single "Problems" SPA filter with per-fault badges. Supersedes #72's api.channel-health-signal decision.
Co-authored-by: Timothy <timothy.look@gmail.com>
Co-committed-by: Timothy <timothy.look@gmail.com>
