feat(groups): editable description, and one source of operator authority

A description could only be set the moment a group was created, so every
group made before anyone thought of one stayed blank for good. The owner
can now edit it from the group's page, and PATCH /v1/groups/{id} takes it.

That endpoint takes the description and nothing else, deliberately. The
name, the visibility and the join policy are the terms members joined on;
a private group that can quietly become public is not the group they
agreed to be in. Changing those needs a decision about who gets told, not
a field on a form — there is a test saying so.

Separately, the legacy operator key is gone. `admin_pk_ed25519` in
node.toml named the operator before the roster existed and was kept so
that an existing deployment would keep working; nothing uses it, and a
second source of node authority is not something to carry around out of
politeness. Authority is the roster, read fresh on every check.

It is removed rather than ignored: a config that still names the key gets
a warning at startup pointing at the file. Dropping it in silence would
refuse invites and file deletion with a signature error that looks like a
bug somewhere else — which is exactly how finding M3 presented.

Two tests were verifying admin operations by naming a key in the context,
which was the legacy path. They now pair an operator into a roster, the
way an operator does. The authority test anchored on the deleted function
and passed vacuously once it disappeared; it states the invariant against
the verifier and the daemon instead.

Also defined .btn-secondary, used in four places and styled in none.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/style.css b/packages/meshbay-hub/src/meshbay_hub/static/style.css
index fab4f55..f83b433 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/style.css
+++ b/packages/meshbay-hub/src/meshbay_hub/static/style.css
@@ -1157,6 +1157,53 @@ button:disabled { opacity: 0.5; cursor: not-allowed; }
 .admin-btn.danger:hover { border-color: var(--error); }
 .admin-btn:disabled { opacity: 0.4; cursor: not-allowed; }
 
+/* Used in four places and never defined, so it rendered as a bare browser
+   button next to styled ones. Same shape as .admin-btn, quieter. */
+.btn-secondary {
+  padding: 4px 10px;
+  border: 1px solid transparent;
+  border-radius: 5px;
+  background: none;
+  color: var(--text-secondary);
+  font-size: 0.82em;
+  cursor: pointer;
+  white-space: nowrap;
+}
+.btn-secondary:hover { border-color: var(--border); color: var(--text); }
+.btn-secondary:disabled { opacity: 0.4; cursor: not-allowed; }
+
+/* Text that acts as a button: the "add a description" affordance should not
+   compete with the group's name for attention. */
+.link-btn {
+  display: inline-flex;
+  align-items: center;
+  gap: 2px;
+  padding: 0;
+  border: none;
+  background: none;
+  color: var(--text-dim);
+  font-size: 0.8em;
+  cursor: pointer;
+}
+.link-btn:hover { color: var(--accent); }
+
+/* The header is a flex row, so a textarea in it collapses to its content
+   width unless told otherwise. */
+.group-desc-edit { margin: 4px 0 6px; width: min(460px, 60vw); min-width: 260px; }
+.group-desc-edit textarea {
+  width: 100%;
+  padding: 6px 8px;
+  border: 1px solid var(--border);
+  border-radius: 5px;
+  background: var(--bg-surface);
+  color: var(--text);
+  font: inherit;
+  font-size: 0.85em;
+  resize: vertical;
+}
+.group-desc-edit textarea:focus { outline: none; border-color: var(--border-focus); }
+.group-desc-edit div { display: flex; gap: 6px; margin-top: 4px; }
+
 .admin-role-select {
   padding: 3px 6px;
   border: 1px solid var(--border);