Configs in the UI are now dynamic, and the channels can register their own configs

• Moved built-in channel config schemas into the channel plugins and wired schema delivery to use the channel registry for config.schema responses.
• Removed base channel schema entries/hints and made the base schema channel-agnostic, with
  channel schemas injected dynamically.
• Replaced Control UI “Connections” with schema-driven “Channels” and cleaned up legacy
  connections controllers/views/routes.
• Added macOS schema support utilities and a generic schema form, then rebuilt Channels + Config
  settings around schema-driven rendering and save/reload state.