feat(design): titles in click surfaces stay selectable (E28 S3e4b)

A button whose text is a title or a name is now `selectable` (FocusSafeButton,
under Pressable and Button): Chrome selects inside a button once it is
user-select: text (measured), and the click that ends a selection, or a press
dragged past the slop, opens nothing. 23 surfaces carry it (cards, rows, people,
channels, playlists, users, views, messages, log lines, description links); the
Plex caption div gets the same guard. A contract test pins every plain Pressable
with its reason, so a new one has to choose.

frontend/src/components/descriptionLinks.tsx

@@ -80,6 +80,7 @@ export function renderDescription(
         const sameVideo = yt.id === opts.currentId;
         out.push(
           <Pressable
+            selectable
             key={key++}
             onClick={() =>
               sameVideo ? opts.onSeek(yt.start ?? 0) : opts.onLoadVideo(yt.id, yt.start)
@@ -135,6 +136,7 @@ export function renderDescription(
         const ts = m[3]!;
         out.push(
           <Pressable
+            selectable
             key={key++}
             onClick={() => opts.onSeek(tsToSeconds(ts))}
             className="text-accent hover:underline"