feat(cli): /put and /get in the interactive chat

/put FILE sends one local file, relative to the current directory or
absolute, into the chat's folder, then posts the application's attachment
message naming it ({"text": "", "attachment": {filename, size, type}}), so
the page shows it as its paperclip's. /get NAME saves a file of that folder,
named from it, into the current directory, never over a file already there.
The chat's folder is the page's rule: the operator's choice while its root
is writable and present, else the first such root; a chat_directory_ack
moves it. A line above the one written in shows the transfer's progress.

Attachment messages, from the page or from /put, read as [file: name, size]
in the room and in `chat`, and as an `attachment` field with --json.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/docs/MESHBAY_DESIGN.md b/docs/MESHBAY_DESIGN.md
index 19510d5..28763af 100644
--- a/docs/MESHBAY_DESIGN.md
+++ b/docs/MESHBAY_DESIGN.md
@@ -3080,7 +3080,11 @@ said meanwhile from the history, each message printed once (a device and nonce
 pair is stored once). `chat` alone opens the interactive chat: the groups, one group's
 conversation IRC-style with what the node pushes arriving live, and back. A
 right-click copies from the conversation (the mouse selection, else the line
-under the pointer) and pastes into the line written in.
+under the pointer) and pastes into the line written in. `/put FILE` uploads
+one local file into the chat's folder and posts the application's attachment
+message naming it; `/get NAME` saves a file of that folder into the current
+directory. The chat's folder follows the page's rule: the operator's choice
+while its root is writable and present, else the first such root.
 
 **Deleting** (`rm`) is `file_delete` signed with the machine's key on the node
 (§5.4): the node accepts the uploading account's devices and the operator's.