EpisodeCommentsGate
Enforces the per-show comments toggle on episode pages at the WordPress filter layer, without calling remove_post_type_support(). When a show’s Enable WordPress comments on episode pages setting is off, closes comments and pings, hides the comment count, and substitutes an empty comments template. This allows each show to be independently gated at request time. Registered as a singleton from Plugin::boot(). Stateless — lookups happen at filter invocation time via ShowMeta::is_comments_enabled().