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, 225 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/style.css b/packages/meshbay-hub/src/meshbay_hub/static/style.css
index 2cb27d0..e1900d9 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/style.css
+++ b/packages/meshbay-hub/src/meshbay_hub/static/style.css
@@ -1000,6 +1000,20 @@ button:disabled { opacity: 0.5; cursor: not-allowed; }
   color: var(--text);
   font-size: 0.95em;
 }
+.settings-label input[type="password"],
+.settings-label input[type="text"],
+.settings-label select {
+  display: block;
+  width: 100%;
+  max-width: 320px;
+  margin-top: 4px;
+  padding: 6px 8px;
+  border-radius: 6px;
+  border: 1px solid var(--border);
+  background: var(--bg-base);
+  color: var(--text);
+  font-size: 0.95em;
+}
 
 .settings-value {
   font-size: 0.9em;
@@ -2399,3 +2413,214 @@ a.transfer-name {
   border-radius: 8px;
   font-size: 0.85em;
 }
+
+/* ── Videos app (video-app.js) ──────────────────────────────────────────────── */
+
+.video-toolbar {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  margin-bottom: 14px;
+}
+.video-toolbar .tb-search { margin-left: auto; }
+
+/* Mode A — poster grid */
+
+.video-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
+  gap: 16px;
+}
+
+.video-tile-slot {
+  min-height: 260px;
+}
+
+.video-card {
+  cursor: pointer;
+  border-radius: 8px;
+  overflow: hidden;
+  background: var(--bg-raised);
+  border: 1px solid var(--border);
+  transition: border-color 0.12s, transform 0.12s;
+}
+.video-card:hover { border-color: var(--accent); transform: translateY(-2px); }
+
+.video-poster {
+  width: 100%;
+  aspect-ratio: 2 / 3;
+  object-fit: cover;
+  display: block;
+  background: var(--bg-surface);
+}
+
+.video-poster-loading {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.video-poster-slot { display: contents; }
+
+.video-thumb {
+  width: 100%;
+  aspect-ratio: 2 / 3;
+  object-fit: cover;
+  display: block;
+  background: var(--bg-surface);
+}
+.video-thumb-empty {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: var(--text-dim);
+}
+.video-thumb-empty .icon { width: 28px; height: 28px; }
+
+.video-card-info { padding: 8px 10px; }
+.video-card-title {
+  font-size: 0.88em;
+  font-weight: 600;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.video-card-sub {
+  font-size: 0.78em;
+  color: var(--text-dim);
+  margin-top: 2px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+/* Detail modal — sits inside the existing .video-overlay */
+
+.video-detail {
+  width: min(720px, 92vw);
+  max-height: calc(100vh - 100px);
+  margin-top: 60px;
+  background: var(--bg-surface);
+  border-radius: 10px;
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+}
+.video-detail .video-top-bar {
+  position: static;
+  background: var(--bg-raised);
+  border-bottom: 1px solid var(--border);
+}
+.video-detail .video-title { color: var(--text); }
+.video-detail .video-close { background: var(--bg-surface); color: var(--text); }
+.video-detail .video-close:hover { background: var(--border); }
+
+.video-detail-body {
+  padding: 16px 20px;
+  overflow-y: auto;
+}
+.video-detail-overview {
+  font-size: 0.9em;
+  color: var(--text);
+  line-height: 1.5;
+}
+.video-detail-facts {
+  font-size: 0.82em;
+  color: var(--text-dim);
+  margin-top: 6px;
+}
+.video-detail-cast {
+  font-size: 0.82em;
+  color: var(--text-secondary);
+  margin-top: 6px;
+}
+
+.video-season-list { margin-top: 14px; }
+.video-season { margin-bottom: 14px; }
+.video-season-header {
+  font-weight: 600;
+  font-size: 0.85em;
+  color: var(--text-dim);
+  margin-bottom: 6px;
+  text-transform: uppercase;
+  letter-spacing: 0.02em;
+}
+.video-episode-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  width: 100%;
+  padding: 8px 10px;
+  background: none;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  color: var(--text);
+  font-size: 0.85em;
+  cursor: pointer;
+  text-align: left;
+  margin-bottom: 4px;
+}
+.video-episode-row:hover { border-color: var(--accent); color: var(--accent); }
+.video-episode-row .icon { width: 14px; height: 14px; flex-shrink: 0; }
+.video-episode-thumb-slot { width: 64px; height: 40px; flex-shrink: 0; }
+.video-episode-thumb {
+  width: 64px;
+  height: 40px;
+  object-fit: cover;
+  border-radius: 4px;
+  display: block;
+  background: var(--bg-raised);
+}
+.video-episode-thumb.video-thumb-empty { border: 1px solid var(--border); }
+.video-episode-label {
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.video-episode-meta {
+  color: var(--text-dim);
+  font-size: 0.9em;
+  flex-shrink: 0;
+}
+
+/* Mode B — flat list */
+
+.video-flat-list { display: flex; flex-direction: column; gap: 4px; }
+
+.video-flat-row {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 6px 8px;
+  border-radius: 6px;
+  cursor: pointer;
+}
+.video-flat-row:hover { background: var(--bg-raised); }
+
+.video-flat-thumb-slot { width: 64px; height: 40px; flex-shrink: 0; }
+.video-flat-thumb {
+  width: 64px;
+  height: 40px;
+  object-fit: cover;
+  border-radius: 4px;
+  display: block;
+  background: var(--bg-raised);
+}
+.video-flat-thumb.video-thumb-empty { border: 1px solid var(--border); }
+
+.video-flat-info { min-width: 0; flex: 1; }
+.video-flat-title {
+  font-size: 0.88em;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.video-flat-sub { font-size: 0.78em; color: var(--text-dim); margin-top: 1px; }
+
+.video-flat-folder { border-bottom: 1px solid var(--border); padding-bottom: 4px; margin-bottom: 4px; }
+.video-flat-chevron { transition: transform 0.12s; flex-shrink: 0; }
+.video-flat-chevron.open { transform: rotate(180deg); }
+.video-flat-season { padding-left: 24px; margin-bottom: 8px; }
+.video-flat-season .video-season-header { margin: 6px 0 4px; }