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/input.go

@@ -103,7 +103,16 @@ func (i inputModel) updateKey(msg tea.KeyMsg) inputModel {
 
 func (i inputModel) view(width int) string {
 	var b strings.Builder
-	b.WriteString(drawerBorderStyle.Render(strings.Repeat("─", width)))
+	label := "capture"
+	prefix := "── "
+	suffix := " "
+	dashCount := width - len(prefix) - len(label) - len(suffix)
+	if dashCount < 0 {
+		dashCount = 0
+	}
+	b.WriteString(drawerBorderStyle.Render(prefix) +
+		hintDescStyle.Render(label) +
+		drawerBorderStyle.Render(suffix+strings.Repeat("─", dashCount)))
 	b.WriteString("\n")
 	b.WriteString(i.ti.View())
 	b.WriteString("\n")