v0.7.0

Changed (breaking — wire protocol)

• Transport / @musubi/client — Connection roots are now identified
  by (module, caller id); the server composes and assigns the wire
  root_id, which the client treats as opaque. Fixes silent state
  corruption when two roots shared a caller id. Duplicate (module, id)
  on one connection is rejected with :already_mounted. Client-side
  dedup removed. Tooling that pinned literal root_id values must
  update. See spec/domains/runtime/features/connection-root-identity.feature (#65).