feat(tui): add split-pane detail, compact date headers, and input drawer

Three layout improvements for better space utilization:

- Compact date headers: date labels render as left gutter column instead
  of standalone lines, saving one line per date group in stream view
- Input drawer: capture bar expands to 4-line drawer with border, hints,
  and live preview of parsed entity/search query
- Split-pane detail: wide terminals (>=100 cols) show list and detail
  side-by-side with h/l focus switching, falling back to full-screen
  detail on narrow terminals

internal/tui/statusbar.go

@@ -47,7 +47,7 @@ func contextHints(m model) string {
 			return "p:promote D:demote c:copy e:edit r:run f:fill !:pin esc:back"
 		}
 	case stateInput:
-		return "enter:submit esc:cancel"
+		return ""
 	case stateTagFilter:
 		return "j/k:nav enter:select esc:cancel"
 	case stateConfirm:
@@ -57,6 +57,12 @@ func contextHints(m model) string {
 	case stateAbsorb:
 		return "j/k:nav enter:absorb esc:cancel"
 	default:
+		if m.splitDetail {
+			if m.focus == focusDetail {
+				return "h:list c:copy e:edit p:promote D:demote !:pin esc:back"
+			}
+			return "l:detail a:add d:del #:filter esc:close ?:help q:quit"
+		}
 		if m.mode == modeCards {
 			return "1:stream 2:cards s:sort tab:intent a:add ?:help q:quit"
 		}