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/en.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
index cbb790f..8c5cbe5 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
@@ -606,6 +606,33 @@ export default {
   'settings_node.photo_roots_save': 'Save',
   'settings_node.shared_directories_title': 'Shared directories',
   'settings_node.shared_directories_hint': 'Folders shared with this group. Toggle read-write to allow uploads, mark as removable for external drives.',
+  'folder_tree.title_single': 'Choose a folder',
+  'folder_tree.title_multi': 'Choose folders',
+  'folder_tree.choose': 'Choose…',
+  'folder_tree.confirm': 'Use these',
+  'folder_tree.expand': 'Expand',
+  'folder_tree.collapse': 'Collapse',
+  'folder_tree.nothing_selected': 'Nothing selected',
+  'folder_tree.empty': 'This group has no shared directories yet.',
+  'folder_tree.writable_only': 'Only read-write directories can be chosen here — files are written to this one.',
+  'folder_tree.no_writable_root': 'This group has no read-write directory. Make one read-write in Shared directories first.',
+  'folder_tree.read_only_blocked': 'Read-only — cannot be written to',
+  'settings_app.save': 'Save',
+  'settings_app.saving': 'Saving…',
+  'settings_app.disabled_hint': 'Turn this app on to configure it.',
+  'settings_app.video_directories_label': 'Video folders',
+  'settings_app.video_directories_hint': 'Where this group\'s films and shows live. Nothing outside them appears in the Videos tab.',
+  'settings_app.music_directories_label': 'Music folders',
+  'settings_app.music_directories_hint': 'Where this group\'s albums live. Nothing outside them appears in the Music tab.',
+  'settings_app.photo_directories_label': 'Photo folders',
+  'settings_app.photo_directories_hint': 'Where this group\'s albums live. Nothing outside them appears in the Photos tab.',
+  'settings_app.chat_directory_label': 'Attachment folder',
+  'settings_app.chat_directory_hint': 'Where files sent in chat are written. Must be a read-write directory.',
+  'settings_app.chat_no_writable_root': 'This group has no read-write directory, so attachments are off.',
+  'settings_app.chat_link_preview_label': 'Link previews',
+  'settings_app.chat_link_preview_hint': 'When a member posts a link, the node fetches the page\'s title and image. That is a request from your machine to a site somebody else chose.',
+  'settings_app.tmdb_token_prompt': 'Sign up on TMDB to generate your own API key.',
+  'settings_app.tmdb_token_link': 'Get a key',
   'settings_node.roots_offline_hint': 'Not connected to the node — changes go through the local node instead, and take effect on its next reload.',
   'settings_node.directories_title': 'App directories',
   'settings_node.directories_hint': 'Which shared folders the Videos, Music and Photos apps use as their entry point(s).',