feat(irc): add interactive setup

feat(gateway): refine Platform._missing_ and platform-connected dispatch

Restricts plugin-name acceptance to bundled plugin scan + registry
(no arbitrary string -> enum-pollution), pulls per-platform connectivity
checks into a _PLATFORM_CONNECTED_CHECKERS lambda map with a clean
_is_platform_connected method, and adds tests covering the checker map,
plugin platform interface, and IRC setup wizard.

ui-tui/src/app/interfaces.ts

@@ -41,10 +41,10 @@ export interface SelectionApi {
   captureScrolledRows: (firstRow: number, lastRow: number, side: 'above' | 'below') => void
   clearSelection: () => void
   copySelection: () => Promise<string>
-  copySelectionNoClear: () => Promise<string>
-  getState: () => unknown
-  version: () => number
-  shiftAnchor: (dRow: number, minRow: number, maxRow: number) => void
+  copySelectionNoClear: () => Promise<string>;
+  getState: () => unknown;
+  version: () => number;
+  shiftAnchor: (dRow: number, minRow: number, maxRow: number) => void;
   shiftSelection: (dRow: number, minRow: number, maxRow: number) => void
 }