feat(tui): status debounce, scroll indicator, drawer label, card grouping

Status messages now use a sequence counter so rapid actions don't
cause premature clearing. Detail pane shows scroll position and
supports pgup/pgdown/g/G. Capture drawer border includes inline
label. Cards view groups by intent (pinned/grab/read/fill) with
gutter labels matching the stream view's date grouping pattern.

internal/tui/commands.go

@@ -58,7 +58,7 @@ type tagsLoadedMsg struct {
 	tags []db.TagCount
 }
 
-type statusClearMsg struct{}
+type statusClearMsg struct{ seq int }
 
 type editorFinishedMsg struct {
 	err error
@@ -270,8 +270,8 @@ func copyResolved(store *db.Store, entityID string, resolved string) tea.Cmd {
 	}
 }
 
-func clearStatusAfter(d time.Duration) tea.Cmd {
+func clearStatusAfter(d time.Duration, seq int) tea.Cmd {
 	return tea.Tick(d, func(time.Time) tea.Msg {
-		return statusClearMsg{}
+		return statusClearMsg{seq: seq}
 	})
 }