feat(node,hub): add Videos group app (poster grid, flat list, TMDB metadata)

Implements docs/mediacenter.md: a "Videos" group application built on the
existing files index rather than a separate catalogue. On the node side,
new indexer enrichment (technical probe, filename/season parsing, thumbnail
generation) runs per-file once an operator has chosen a video_root for the
group, plus a TMDB client for on-demand poster/metadata lookups (never
client-side, thumbnails delivered over the existing chunk path). On the hub
side, a new video-app.js renders a lazily-mounted poster grid or a
thumbnail-only flat list, with TMDB entirely optional per group.

Along the way: the global apps registry now drives Settings' default-tab
picker instead of a hardcoded list, and the video_root is configured from
group Settings (like uploads) rather than from Files, with the node
refusing to run any TMDB/thumbnail work until one is set.

Fixes several bugs found via live testing against a real library, notably
a race between two effects writing the same "image ready" state that could
leave a poster grid spinning forever on a same-tab revisit — see
mediacenter.md §5.4 for the full account of each one.

1 files changed, 29 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 a83b067..ebdb3e2 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
@@ -77,6 +77,7 @@ export default {
   'group.default_name': 'Group',
   'group.tab_files': 'Files',
   'group.tab_chat': 'Chat',
+  'group.tab_video': 'Videos',
   'group.tab_members': 'Members',
   'group.tab_settings': "Settings",
   'members.danger_leave_hint': "You will lose access to this group's files and chat.",
@@ -154,6 +155,18 @@ export default {
   'group.upload_indexing': 'indexing…',
   'video.err_transport': 'Transport not connected',
   'video.err_mse': 'Codec not supported for streaming: {codec}',
+  'video.mode_poster': 'Posters',
+  'video.mode_flat': 'Flat list',
+  'video.empty': 'No videos found.',
+  'video.no_root_configured': 'No Videos root folder is set for this group yet — an operator can choose one in Settings.',
+  'video.director': 'Director',
+  'video.specials': 'Specials',
+  'video.season_n': 'Season {n}',
+  'video.episode_n': 'Episode {n}',
+  'video.n_episodes': {
+    one: '{n} episode',
+    other: '{n} episodes',
+  },
 
   // LAN cast
   'cast.start': 'Cast to device',
@@ -396,6 +409,22 @@ export default {
   'settings_node.scan_save': 'Save',
   'settings_node.scan_saving': 'Saving…',
   'settings_node.scan_saved': 'Saved.',
+  'settings_node.tmdb_title': 'TMDB metadata',
+  'settings_node.tmdb_hint': 'Lets the Videos app show posters, overviews and cast from TMDB. Off means thumbnail-only browsing, with no request to a third party.',
+  'settings_node.tmdb_enabled': 'Enabled',
+  'settings_node.tmdb_disabled': 'Disabled',
+  'settings_node.tmdb_token_label': 'Custom API token (optional)',
+  'settings_node.tmdb_token_placeholder': 'Leave blank to use the shipped default',
+  'settings_node.tmdb_token_customized': 'A custom token is set.',
+  'settings_node.tmdb_token_default': 'Using the shipped default token.',
+  'settings_node.tmdb_save': 'Save',
+  'settings_node.tmdb_language_label': 'Language',
+  'settings_node.tmdb_language_hint': 'Applies to everyone — one shared cache, not a per-viewer request.',
+  'settings_node.video_root_title': 'Videos root folder',
+  'settings_node.video_root_hint': 'Which folder (or subfolder) the Videos app treats as its entry point for this group. Nothing shows in Videos, and no TMDB lookups run, until one is chosen.',
+  'settings_node.video_root_none': '— none chosen —',
+  'settings_node.video_root_save': 'Save',
+  'settings_node.video_root_change_confirm': 'Changing the Videos root replaces what every member sees in the Videos tab. Continue?',
 
   // Members
   'members.col_role': 'Role',