fix(node): remove --upload-dir rather than document it

Caught in review, and the review was right. The previous commit documented the
flag as deprecated so that `--help` and the man page would agree. That solved
the wrong problem: the flag contradicts the model this whole refactor exists to
establish, and the coherent answer was to delete it.

It wrote `upload_dir` into a *brand-new* `[[groups]]` block, and
`GroupConfig.__post_init__` reads that key by forcing every other root
read-only and appending that path as the one writable one. So
`group add --dir X --writable --upload-dir Y` silently made X read-only — two
mechanisms deciding which directories accept uploads, one of them invisible, in
a group created after the model that replaced it.

Gone from the CLI, from `ops.attach_group`, from the loopback API and from the
MNP `group_attach` payload, which now carries `writable` instead. The *read*
path in `config.py` is deliberately untouched: an existing node.toml using
`upload_dir` must keep working, and that is the only legitimate use left. The
man page says so under the config key, and no longer lists an option.

The test that guarded the deprecation wording now guards its absence — and
earned itself immediately by finding a `group add` usage string still offering
the flag.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011pvMdvLBG92jyhvD5pD6us

1 files changed, 9 insertions, 15 deletions

diff --git a/man/meshbay-node.1 b/man/meshbay-node.1
index 890da89..7c7cf96 100644
--- a/man/meshbay-node.1
+++ b/man/meshbay-node.1
@@ -280,15 +280,6 @@ and makes the node treat the directory suddenly disappearing as an
 unannounced eject rather than as a deletion.
 .
 .TP
-\fB\-\-upload\-dir\fR \fIpath\fR
-Deprecated. A second, read\-write root, used with
-.BR "group add" ,
-from before roots carried their own read\-write flag. Setting it makes every
-other root of that group read\-only. Use
-.B "meshbay\-node root add" \fIpath\fR \fB\-\-writable\fR
-instead.
-.
-.TP
 \fB\-\-name\fR \fIname\fR
 Explicit name for a root, used with
 .BR "root add" .
@@ -442,12 +433,15 @@ named after the directory's basename. Cannot be combined with
 .
 .TP
 .B upload_dir
-Deprecated. A separate filesystem path for uploads, from before roots
-carried their own read\-write flag. A configuration still using it is
-read as a second, writable root and every other root is forced
-read\-only. Use
-.B writable
-on the intended root instead.
+Deprecated, and read only. A separate filesystem path for uploads, from before
+roots carried their own read\-write flag. An existing configuration using it
+still works: it is read as a second, writable root, and every other root of
+that group is forced read\-only. Nothing writes it any more \(em there is no
+\fB\-\-upload\-dir\fR option \(em because that would be a second mechanism
+deciding which directories accept uploads, silently overriding
+.BR writable .
+To have two writable directories, mark them both
+.BR "writable = true" .
 .
 .TP
 .B visibility