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/styles.go

@@ -101,4 +101,8 @@ var (
 
 	checkPendingStyle = lipgloss.NewStyle().
 				Foreground(dim)
+
+	searchPillStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.AdaptiveColor{Light: "#E06C75", Dark: "#E06C75"}).
+			Bold(true)
 )