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/nl.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
index cdd4720..7070288 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
@@ -830,6 +830,33 @@ export default {
   'settings_node.photo_roots_save': 'Opslaan',
   'settings_node.shared_directories_title': 'Gedeelde mappen',
   'settings_node.shared_directories_hint': 'Mappen gedeeld met deze groep. Schakel lezen-schrijven in om uploads toe te staan, markeer als verwijderbaar voor externe schijven.',
+  'folder_tree.title_single': 'Kies een map',
+  'folder_tree.title_multi': 'Kies mappen',
+  'folder_tree.choose': 'Kiezen…',
+  'folder_tree.confirm': 'Gebruiken',
+  'folder_tree.expand': 'Uitklappen',
+  'folder_tree.collapse': 'Inklappen',
+  'folder_tree.nothing_selected': 'Niets geselecteerd',
+  'folder_tree.empty': 'Deze groep heeft nog geen gedeelde mappen.',
+  'folder_tree.writable_only': 'Hier zijn alleen lees-schrijfmappen te kiezen — er wordt in geschreven.',
+  'folder_tree.no_writable_root': 'Deze groep heeft geen beschrijfbare map. Zet er eerst één op lezen-schrijven bij Gedeelde mappen.',
+  'folder_tree.read_only_blocked': 'Alleen-lezen — kan niet worden beschreven',
+  'settings_app.save': 'Opslaan',
+  'settings_app.saving': 'Opslaan…',
+  'settings_app.disabled_hint': 'Zet deze app aan om hem in te stellen.',
+  'settings_app.video_directories_label': 'Videomappen',
+  'settings_app.video_directories_hint': 'Waar de films en series van deze groep staan. Niets daarbuiten verschijnt op het tabblad Video\'s.',
+  'settings_app.music_directories_label': 'Muziekmappen',
+  'settings_app.music_directories_hint': 'Waar de albums van deze groep staan. Niets daarbuiten verschijnt op het tabblad Muziek.',
+  'settings_app.photo_directories_label': 'Fotomappen',
+  'settings_app.photo_directories_hint': 'Waar de albums van deze groep staan. Niets daarbuiten verschijnt op het tabblad Foto\'s.',
+  'settings_app.chat_directory_label': 'Map voor bijlagen',
+  'settings_app.chat_directory_hint': 'Waar in de chat verstuurde bestanden worden geschreven. Moet een lees-schrijfmap zijn.',
+  'settings_app.chat_no_writable_root': 'Deze groep heeft geen beschrijfbare map, dus bijlagen staan uit.',
+  'settings_app.chat_link_preview_label': 'Linkvoorbeelden',
+  'settings_app.chat_link_preview_hint': 'Als een lid een link plaatst, haalt de node de titel en afbeelding van de pagina op. Dat is een verzoek vanaf uw machine naar een site die iemand anders koos.',
+  'settings_app.tmdb_token_prompt': 'Meld u aan bij TMDB om uw eigen API-sleutel te maken.',
+  'settings_app.tmdb_token_link': 'Sleutel ophalen',
   'settings_node.roots_offline_hint': 'Niet verbonden met de node — wijzigingen gaan via de lokale node en worden bij de volgende herlaadbeurt actief.',
   'settings_node.directories_title': 'App-mappen',
   'settings_node.directories_hint': 'Gedeelde mappen, en welke daarvan de Video\'s-, Muziek- en Foto\'s-apps als eigen startpunt(en) gebruiken.',