feat(client): Phase 2 — per-app settings panes, folder tree, multi-directory

Each app's settings were inlined in `group-settings.js` — TMDB, MusicBrainz,
and one folder picker per app, each with its own draft state and save handler
saying the same thing about a different key. They are one file per app now,
reached through the `apps.js` registry, and the page that renders them names no
application at all: adding one is a registry entry and a settings file.

The line between the two is what makes that true. What every app has — folders
— the page does generically, through one `saveDirectories` bound to the app.
What one app alone has, its pane does itself with the transport it is handed.
An app that only needs directories touches neither `group-settings.js` nor
`group-page.js`, which is `test_app_settings_plugin.py`'s subject.

`settings-ui.js` exists because a pane importing the page that renders it is a
cycle, and ES modules answer that with a temporal-dead-zone ReferenceError at
first render — a component that silently does not appear, the fault already
recorded in CLAUDE.md about hook ordering.

The flat depth-indented `<select>` of every folder in the library becomes a
modal tree. It asks the node for nothing: the tree is derived from paths the
client already holds, so it shows exactly what the group's index contains and
adds no folder-browsing protocol. For Chat's attachment folder — the one
directory that is written to rather than read — read-only roots are greyed
out, so the node's refusal arrives before the operator picks rather than when
somebody sends a file.

Videos and Music take a list of folders. A library on two drives could not be
described before; the only recourse was pointing the app at a parent containing
both, which pulls in everything else under it. The scalar shapes survive on the
wire alone, for a node speaking MNP 1.0, and the client reads them as a
one-element list.

Two things the tests caught that I would not have:

`test_asset_versioning` — six new modules were missing from `_ASSETS`. Reached
through the registry rather than imported by name, they are exactly the files
nothing else would notice changing, and a stale one is served from cache with
no version bump.

And `node --check foo.js` does **not** reliably report a module syntax error:
it accepted `${/* ... */''}` — htm template syntax pasted into a plain object
literal — and reported success. A `.mjs` copy forces the module parser and
reports it. The suite had no syntax check at all, which is how that reached a
file; `test_spa_syntax.py` does it for every module now, and pins that the
loose path is not what it uses.

Suite: 12 failures, all pre-existing.

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

1 files changed, 27 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
index 4e60eb9..bee4ae9 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
@@ -832,6 +832,33 @@ export default {
   'settings_node.photo_roots_save': 'Enregistrer',
   'settings_node.shared_directories_title': 'Répertoires partagés',
   'settings_node.shared_directories_hint': 'Dossiers partagés avec ce groupe. Activez lecture-écriture pour autoriser les envois, marquez comme amovible pour les disques externes.',
+  'folder_tree.title_single': 'Choisir un dossier',
+  'folder_tree.title_multi': 'Choisir des dossiers',
+  'folder_tree.choose': 'Choisir…',
+  'folder_tree.confirm': 'Utiliser',
+  'folder_tree.expand': 'Déplier',
+  'folder_tree.collapse': 'Replier',
+  'folder_tree.nothing_selected': 'Rien de sélectionné',
+  'folder_tree.empty': 'Ce groupe n\'a pas encore de répertoire partagé.',
+  'folder_tree.writable_only': 'Seuls les répertoires en lecture-écriture sont proposés ici — des fichiers y sont écrits.',
+  'folder_tree.no_writable_root': 'Ce groupe n\'a aucun répertoire en écriture. Activez d\'abord lecture-écriture dans Répertoires partagés.',
+  'folder_tree.read_only_blocked': 'Lecture seule — écriture impossible',
+  'settings_app.save': 'Enregistrer',
+  'settings_app.saving': 'Enregistrement…',
+  'settings_app.disabled_hint': 'Activez cette application pour la configurer.',
+  'settings_app.video_directories_label': 'Dossiers vidéo',
+  'settings_app.video_directories_hint': 'Où vivent les films et séries de ce groupe. Rien en dehors n\'apparaît dans l\'onglet Vidéos.',
+  'settings_app.music_directories_label': 'Dossiers musique',
+  'settings_app.music_directories_hint': 'Où vivent les albums de ce groupe. Rien en dehors n\'apparaît dans l\'onglet Musique.',
+  'settings_app.photo_directories_label': 'Dossiers photo',
+  'settings_app.photo_directories_hint': 'Où vivent les albums de ce groupe. Rien en dehors n\'apparaît dans l\'onglet Photos.',
+  'settings_app.chat_directory_label': 'Dossier des pièces jointes',
+  'settings_app.chat_directory_hint': 'Où sont écrits les fichiers envoyés dans le chat. Doit être un répertoire en lecture-écriture.',
+  'settings_app.chat_no_writable_root': 'Ce groupe n\'a aucun répertoire en écriture : les pièces jointes sont désactivées.',
+  'settings_app.chat_link_preview_label': 'Aperçus des liens',
+  'settings_app.chat_link_preview_hint': 'Quand un membre poste un lien, le nœud récupère le titre et l\'image de la page. C\'est une requête depuis votre machine vers un site choisi par quelqu\'un d\'autre.',
+  'settings_app.tmdb_token_prompt': 'Créez un compte TMDB pour générer votre propre clé d\'API.',
+  'settings_app.tmdb_token_link': 'Obtenir une clé',
   'settings_node.roots_offline_hint': 'Non connecté au nœud — les changements passent par le nœud local et prennent effet à son prochain rechargement.',
   'settings_node.directories_title': 'Répertoires des applications',
   'settings_node.directories_hint': 'Quel(s) dossier(s) partagés les applications Vidéos, Musique et Photos utilisent comme leur(s) propre(s) point(s) d\'entrée.',