fix: correct doc comment — path goes to stdout not stderr

hive-forge/src/verbs/attachment_get.rs

@@ -4,7 +4,8 @@
 //! `/attachments/<uuid>` (as it appears in comment markdown).
 //!
 //! Default output path: `/tmp/forge-attachment-<uuid>`. Prints the
-//! resolved path to stderr so callers can locate it easily.
+//! resolved path to stdout so callers can capture it
+//! (`path=$(hive-forge attachment-get <uuid>)`).
 
 use std::io::Write as _;
 use std::path::PathBuf;