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/ja.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
index 7890ab7..75a3aa2 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
@@ -812,6 +812,33 @@ export default {
   'settings_node.photo_roots_save': '保存',
   'settings_node.shared_directories_title': '共有ディレクトリ',
   'settings_node.shared_directories_hint': 'このグループと共有されているフォルダー。読み書きを切り替えてアップロードを許可し、外付けドライブにはリムーバブルを設定します。',
+  'folder_tree.title_single': 'フォルダーを選択',
+  'folder_tree.title_multi': 'フォルダーを選択',
+  'folder_tree.choose': '選択…',
+  'folder_tree.confirm': '決定',
+  'folder_tree.expand': '展開',
+  'folder_tree.collapse': '折りたたむ',
+  'folder_tree.nothing_selected': '未選択',
+  'folder_tree.empty': 'このグループにはまだ共有ディレクトリがありません。',
+  'folder_tree.writable_only': 'ここには読み書き可能なディレクトリしか選べません — ファイルが書き込まれます。',
+  'folder_tree.no_writable_root': 'このグループには書き込み可能なディレクトリがありません。まず「共有ディレクトリ」で読み書きを有効にしてください。',
+  'folder_tree.read_only_blocked': '読み取り専用 — 書き込みできません',
+  'settings_app.save': '保存',
+  'settings_app.saving': '保存中…',
+  'settings_app.disabled_hint': 'このアプリを有効にすると設定できます。',
+  'settings_app.video_directories_label': '動画フォルダー',
+  'settings_app.video_directories_hint': 'このグループの映画や番組がある場所です。それ以外は動画タブに表示されません。',
+  'settings_app.music_directories_label': '音楽フォルダー',
+  'settings_app.music_directories_hint': 'このグループのアルバムがある場所です。それ以外は音楽タブに表示されません。',
+  'settings_app.photo_directories_label': '写真フォルダー',
+  'settings_app.photo_directories_hint': 'このグループのアルバムがある場所です。それ以外は写真タブに表示されません。',
+  'settings_app.chat_directory_label': '添付ファイルのフォルダー',
+  'settings_app.chat_directory_hint': 'チャットで送られたファイルの書き込み先です。読み書き可能なディレクトリである必要があります。',
+  'settings_app.chat_no_writable_root': 'このグループには書き込み可能なディレクトリがないため、添付は無効です。',
+  'settings_app.chat_link_preview_label': 'リンクのプレビュー',
+  'settings_app.chat_link_preview_hint': 'メンバーがリンクを投稿すると、ノードがページのタイトルと画像を取得します。これは他人が選んだサイトへの、あなたのマシンからのリクエストです。',
+  'settings_app.tmdb_token_prompt': 'TMDB に登録して、自分の API キーを発行してください。',
+  'settings_app.tmdb_token_link': 'キーを取得',
   'settings_node.roots_offline_hint': 'ノードに接続していません — 変更はローカルノード経由で行われ、次回の再読み込みで反映されます。',
   'settings_node.directories_title': 'アプリのディレクトリ',
   'settings_node.directories_hint': '共有フォルダと、動画・音楽・写真の各アプリがそれぞれの起点として使用するフォルダです。',