fix: the chat tab no longer scrolls, and a group is listed or invite-only

**The chat tab was 8px too tall, at every window size.** The panel is sized from
JS to `viewport - top - 16`, which puts its bottom 16px above the fold — but it
sits inside `.main`, which adds 24px of padding below it. Eight pixels of
document past the window, whatever the window. Measured at 700, 900 and 1200:
`scrollHeight` 708, 908, 1208.

This is the second one of these — the sign-in card was `.page-center` and
`.layout` each reserving `100vh - 52px` — so it is now measured in the suite
rather than reasoned about. `tests/harness/scroll_probe.py` renders the real
markup against the real stylesheet and **runs the real `fit()` lifted out of
`app.js`**: a copy of the formula in a test would go on passing after the
original changed, which is exactly the bug being guarded.

The fix does not encode 24 anywhere. The first pass runs as before, then the
leftover is measured and taken off, so anything added below the panel later is
absorbed the same way. Now `scrollHeight == innerHeight` at all three heights,
nothing below the fold, and the panel still fills the room it has — that last
one has its own test, because shrinking the chat to 240px would satisfy every
other assertion here and be useless.

The Settings tab was measured too and is **not** a bug: it fits at 1200px and
overflows only when its content is genuinely taller than the window.

**Group creation asked one question twice.** Visibility and admission were
separate selectors that could only ever be set together — picking Public reached
over and set the policy — and two of the four combinations are meaningless. The
API already refused public+invite with a 422, so the form could build a request
that could not succeed. Private+open was accepted and should not have been: a
group anyone may join that nobody can find is a listing with the listing
removed, since joining goes through the node and there is no link to pass
around.

So: one selector, "who can join", and the request derives the rest. The API now
refuses the other impossible pair as well, with a message that says which way to
resolve it. Six locale strings the visibility box owned are deleted rather than
left unread in ten files, and the two surviving descriptions now say what each
choice means for who can *find* the group — with the word "public" gone from the
page, nothing else would have said it, and someone would publish a group without
meaning to.

865 tests pass.

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

1 files changed, 2 insertions, 8 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
index 497cc4a..1af0eb1 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
@@ -322,16 +322,11 @@ export default {
   'create_group.title': 'Groep aanmaken',
   'create_group.name': 'Groepsnaam',
   'create_group.name_placeholder': 'bijv. Familiefotos, Projectbestanden...',
-  'create_group.visibility': 'Zichtbaarheid',
-  'create_group.private': 'Privé',
-  'create_group.private_desc': 'Alleen uitgenodigde leden zien de bestanden en hebben er toegang toe',
-  'create_group.public': 'Openbaar',
-  'create_group.public_desc': 'Iedereen kan deze groep vinden en doorbladeren',
   'create_group.join_policy': 'Toetredingsbeleid',
   'create_group.invite': 'Alleen op uitnodiging',
-  'create_group.invite_desc': 'Leden moeten door een beheerder worden uitgenodigd',
+  'create_group.invite_desc': "Leden moeten door een beheerder worden uitgenodigd. De groep staat niet in de openbare lijst.",
   'create_group.open': 'Open (iedereen kan deelnemen)',
-  'create_group.open_desc': 'Iedereen kan zonder goedkeuring deelnemen',
+  'create_group.open_desc': "Staat bij de openbare groepen — iedereen kan de groep vinden en zonder goedkeuring deelnemen.",
   'create_group.description': 'Beschrijving',
   'create_group.description_hint': 'Waar gaat deze groep over? (optioneel)',
   'create_group.submit': 'Aanmaken',
@@ -452,5 +447,4 @@ export default {
   'group.leave_confirm': '„{name}” verlaten? U verliest de toegang tot de bestanden en de chat ervan. Bestanden die u hebt geüpload blijven op de node, en de node houdt de voor u vastgezette identiteit tot zijn beheerder die weghaalt.',
   'profile.title': 'Profiel',
   'usermenu.profile': 'Profiel',
-  'create_group.public_is_open': 'Iedereen kan een openbare groep vinden en eraan deelnemen. Wilt u kiezen wie binnenkomt, maak de groep dan privé.',
 };