feat: remove legacy OpenCode runtime

Cut product flows over to Coding/Pi and retain only the migration-owned v1 boundary. Promote supported native optional packages because electron-builder omitted pnpm transitive optional closure from the packaged ASAR.

src/lib/api-client.ts

@@ -29,7 +29,6 @@ const UNIFIED_CHANNELS = new Set<string>([
   'app:version',
   'app:name',
   'app:platform',
-  'opencode:status',
   'settings:getAll',
   'settings:get',
   'settings:set',
@@ -135,7 +134,7 @@ export async function invokeIpcWithRetry<T>(
 }
 
 export function initializeDefaultTransports(): void {
-  // IPC is the only renderer-to-main transport in the opencode-based app.
+  // IPC is the only renderer-to-main transport in the desktop app.
 }
 
 export function toUserMessage(error: unknown): string {