Docs: speech-to-text and text-to-speech recipes for a panel's mic and speaker

faster-whisper and piper as plain Function nodes, the mic -> STT -> logic ->
TTS -> speaker wiring, the Modules manifest they need (uv pip compile, av<19)
and measured sizes, memory and CPU times. Modules docs now say uv pip sync
installs no dependencies.

docs/interface/dashboards.md

@@ -420,7 +420,8 @@ to 640×360. Re-encode other clips with the [clip recipe](../code/nodes.md#makin
 The device decides what the panel's [I/O](#the-devices-own-io) port names
 mean. openpanel serves `gpio.<n>`, `backlight`, `touch`, `mic` and `speaker`,
 lists each one's `config` in its README and ignores any other name. A browser
-screen serves none of them.
+screen serves none of them. The [speech recipe](../code/nodes.md#speech-to-and-from-a-panel)
+turns `mic` into text and text into `speaker`.
 
 ### The device's own I/O