feat(catalogue): tune a single-station catalogue on switch

README.md

@@ -67,7 +67,9 @@ implemented here from public endpoints and open protocols.
 - **Favourites** that float to the top, remembered between runs.
 - **Pluggable catalogues** — one `providers` module per radio network, with a
   `p` picker in the UI, `--provider` on the command line, and the choice
-  remembered per catalogue (including the last station you tuned).
+  remembered per catalogue (including the last station you tuned). Switching to
+  a single-station catalogue tunes it straight away; a multi-station one waits
+  for `enter`.
 - **A hero per catalogue** — the top-left art is the catalogue's own name in a
   shared half-block font: SomaFM in the spectrum gradient, tilderadio in the
   terminal's default colour, Bassdrive in its two blues. Every hero is three