Turn handoff can name files to copy into the home directory

What

A turn handoff passes an unfinished turn to a cloud worker to finish. It gains two internal capabilities:

• file_names: a turn_handoff request can carry an optional list of up to 16 entries, each {file_uuid, name}. A worker that announces file_names: true in turn_handoff_available copies the attached files it has already downloaded into the session's home directory under those names before the handed-off tool calls run. The names are checked when the handoff is validated.
• home_files: a worker can announce support for stage_file requests to /uploads/.home/<path>, which end up at /home/claude/<path>.
• Marked live: the last assistant message of a handed-off turn is now marked handedOffLive.

The schema text is marked internal, and its permission description drops the words "ordinary" and "exactly as calls its own model emitted".

Why

This affects only cloud and remote sessions. Files can now be placed in the worker's home directory under the expected names before the handed-off work runs.