A named, VM-wide lookup table from an arbitrary String.t() name to a %Logos.Runtime{}. Its main consumer is mix logos.remsh: a host app that starts distributed (--sname/--name + cookie) registers its Runtime(s) here under a name, and a logos.remsh session attached to that node looks up "the Runtime the host app wants exposed" by name rather than needing a direct reference passed around from process to process.

Storage-shape decision

Backed by a bare :ets table (:named_table, :public, :set) -- deliberately not Elixir's Registry module, which is built for registering processes (keys map to {pid, value}, entries vanish automatically when the owning process dies) -- a %Logos.Runtime{} is plain data (an ETS table reference wrapped in a struct, see Logos.Runtime's own moduledoc), not a process, so there is no "owning process" for Registry's automatic cleanup semantics to hook into. A bare named ETS table is the simplest thing that actually fits: register/lookup/list are three one-line ETS operations, and unlike every Logos.Runtime table itself (deliberately not :named_table, per that module's own moduledoc, to avoid a global-singleton trap), this module's whole purpose is to be a single global, VM-wide singleton directory -- "the host app's named Runtimes" is inherently one thing per VM, not one per embedding instance. start!/0 is idempotent (safe to call more than once, e.g. from multiple mix tasks in the same VM, or from tests) so nothing but the first caller actually creates the table.