refactor(cli): use Response(stream).text() instead of Bun.readableStreamToText

bun-install.ts streamToText() was reachable from the plugin bundle via
the cli/config-manager barrel re-export. Replace with the WHATWG
standard `new Response(stream).text()` pattern which works
identically in Bun and Node and avoids the last raw Bun.* runtime
call in dist/index.js.

src/cli/config-manager/bun-install.ts

@@ -26,10 +26,6 @@ declare function clearTimeout(timeout: number): void
 
 type ProcessOutputStream = ReturnType<typeof spawnWithWindowsHide>["stdout"]
 
-declare const Bun: {
-  readableStreamToText(stream: NonNullable<ProcessOutputStream>): Promise<string>
-}
-
 export interface BunInstallResult {
   success: boolean
   timedOut?: boolean
@@ -50,7 +46,7 @@ function readProcessOutput(stream: ProcessOutputStream): Promise<string> {
     return Promise.resolve("")
   }
 
-  return Bun.readableStreamToText(stream)
+  return new Response(stream).text()
 }
 
 function logCapturedOutputOnFailure(outputMode: BunInstallOutputMode, output: BunInstallOutput): void {