Voice lists were a single flat set from LITELLM_TTS_VOICES, so picking a
model could leave an incompatible voice selected and the request would
fail at the gateway. Voices are now resolved per model family (Kokoro,
Kitten, Supertonic, Groq Orpheus EN/AR), with a compatibility check that
falls back through user → admin → env → first valid voice. Groq Orpheus
requests also pin response_format to wav.
Also refreshes the cardiac/respiratory auscultation samples, extends the
well-visit component, and fixes the Android launch theme background
(@null → colorPrimary) so the splash does not flash through.
NOTE: this is in-progress work that was already sitting uncommitted in
the working tree; it is committed here as-is so the tree was clean for
the release bump.
