feat(tui): add search via capture bar and absorb flow

Search uses existing parse grammar ?prefix — type `?query #tag` in
capture bar to filter entities client-side. Substring match on
body+title+description with AND tag filtering. Esc clears search.

Absorb via m key on fluid entities — opens source picker showing all
other entities, enter merges source into target. Uses existing
store.Absorb() backend.

internal/tui/statusbar.go

@@ -27,7 +27,7 @@ func countText(m model) string {
 	if m.mode == modeCards {
 		total = len(m.cards.filtered)
 	} else {
-		total = len(m.list.entities)
+		total = len(m.list.displayEntities())
 	}
 	if m.filterTag != "" {
 		return fmt.Sprintf("%d entities #%s", total, m.filterTag)
@@ -47,10 +47,12 @@ func contextHints(m model) string {
 		return "y:confirm n:cancel"
 	case statePromote:
 		return "j/k:nav enter:select esc:cancel"
+	case stateAbsorb:
+		return "j/k:nav enter:absorb esc:cancel"
 	default:
 		if m.mode == modeCards {
 			return "1:stream 2:cards s:sort tab:intent a:add ?:help q:quit"
 		}
-		return "1:stream 2:cards a:add d:del x:todo #:filter ?:help q:quit"
+		return "1:stream 2:cards a:add/?search m:absorb d:del #:filter ?:help q:quit"
 	}
 }