feat(tui): add cards view, mode switching, promote picker, and card detail

Stream/cards toggle with 1/2 keys. Cards view with intent filtering
(tab cycles grab/read/fill/all), sort cycling (s key), pinned-first
ordering, and affordance badges. Promote picker (p key) with card type
selection and auto-detection from body content. Detail view renders
card_data per type: checklist steps, template slots, decision fields,
link URLs.

Extracts generateCardData to internal/carddata for reuse across cmd
and tui packages.

internal/tui/help.go

@@ -12,7 +12,13 @@ func renderHelp(width, height int) string {
 			{"g/G home/end", "top / bottom"},
 			{"pgup/pgdn", "page up / down"},
 			{"enter", "view detail"},
-			{"esc", "back / cancel"},
+			{"esc", "back / clear filter"},
+		}},
+		{"Views", [][2]string{
+			{"1", "stream view"},
+			{"2", "cards view"},
+			{"s", "cycle sort (cards)"},
+			{"tab", "cycle intent (cards)"},
 		}},
 		{"Actions", [][2]string{
 			{"a", "add entity"},
@@ -20,6 +26,7 @@ func renderHelp(width, height int) string {
 			{"x", "toggle todo completion"},
 			{"!", "toggle pin"},
 			{"#", "filter by tag"},
+			{"p", "promote to card"},
 		}},
 		{"Detail View", [][2]string{
 			{"p", "promote to card"},