fix(format): set stdin/stdout/stderr to ignore for formatter subprocesses

ChildProcess.make defaults to "pipe" for all stdio streams. Formatters
that wait on stdin EOF or write enough output to fill pipe buffers would
hang. Matches the original Process.spawn behavior.

packages/opencode/src/format/index.ts

@@ -114,6 +114,9 @@ export namespace Format {
                       cwd: Instance.directory,
                       env: item.environment,
                       extendEnv: true,
+                      stdin: "ignore",
+                      stdout: "ignore",
+                      stderr: "ignore",
                     }),
                   )
                   .pipe(