feat(tui): always-visible capture bar with focus cycling

Replace drawer-based input with permanent capture bar at bottom.
Focus defaults to capture on startup — open nib, start typing.

- Remove stateInput; route via focusCapture/focusList/focusDetail
- Tab cycles: capture → list → detail (split) → capture
- Esc cascades: clear search → clear filter → focus capture
- Capture bar shows blinking cursor when focused, dims when not
- Intent cycling moved from tab to i (tab now cycles focus)
- Parse preview shown inline in status bar while typing
- Content area constant height (no layout thrash from drawer)

internal/tui/help.go

@@ -7,21 +7,31 @@ func renderHelp(width, height int) string {
 		title string
 		binds [][2]string
 	}{
+		{"Focus", [][2]string{
+			{"tab", "cycle focus: capture → list → detail"},
+			{"esc", "back / clear filter / to capture"},
+			{"a", "focus capture bar"},
+		}},
+		{"Capture Bar", [][2]string{
+			{"enter", "submit (or browse if empty)"},
+			{"?…", "search (type ?query)"},
+			{"-", "todo prefix"},
+			{"@", "event prefix"},
+			{"!", "reminder prefix"},
+		}},
 		{"Navigation", [][2]string{
 			{"j/k ↑/↓", "move cursor"},
 			{"g/G home/end", "top / bottom"},
 			{"pgup/pgdn", "page up / down"},
 			{"enter", "view detail"},
-			{"esc", "back / clear filter"},
 		}},
 		{"Views", [][2]string{
 			{"1", "stream view"},
 			{"2", "cards view"},
 			{"s", "cycle sort (cards)"},
-			{"tab", "cycle intent (cards)"},
+			{"i", "cycle intent (cards)"},
 		}},
 		{"Actions", [][2]string{
-			{"a", "add entity (or ?query to search)"},
 			{"d", "delete (with confirm)"},
 			{"x", "toggle todo completion"},
 			{"!", "toggle pin"},