gallery(audio-cpp): declare audio_transform on the chatterbox entry

Chatterbox advertises VoiceCloning AND VoiceConversion
(src/models/chatterbox), and the entry's own description already said so, but
known_usecases listed only tts. /audio/transform selects its default model by
FLAG_AUDIO_TRANSFORM, so voice conversion was reachable only by naming the
model explicitly and was invisible to every usecase-driven surface. It is the
one audio.cpp task with a shipped gallery model and no way to find it.

Verified against the real model rather than inferred from the capability list:
AudioTransform with chatterbox-q8_0, speech as audio_path and a speaker clip
as reference_path, returns a 5.08 s 24 kHz mono WAV at -25.5 dB mean and zero
stems, which is the single-output shape voice conversion should have.

The description now says which endpoint reaches that half and warns that
installing this next to a source-separation model gives /audio/transform two
candidates, so the model should be named rather than defaulted.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Assisted-by: Claude:claude-opus-5 [Claude Code]

gallery/index.yaml

@@ -46772,6 +46772,13 @@
     file on disk is treated as a named preset and the request is refused with a
     message saying so.
 
+    The voice-conversion half is reached through /audio/transform rather than
+    /v1/audio/speech: post the speech to convert as `audio` and the target
+    speaker's clip as `reference`. That is why this entry declares
+    audio_transform alongside tts. With both this and a source-separation model
+    installed, /audio/transform has two candidates, so name the model
+    explicitly rather than relying on the default pick.
+
     Q8_0 rather than 16-bit because upstream's tested-status table records the
     same result for both (Pass, ASR match with drift) and this build is half
     the size.
@@ -46782,6 +46789,7 @@
     - tts
     - text-to-speech
     - voice-cloning
+    - voice-conversion
     - gguf
     - ggml
     - quantized
@@ -46790,6 +46798,7 @@
     backend: audio-cpp
     known_usecases:
       - tts
+      - audio_transform
     name: audio-cpp-chatterbox
     parameters:
       model: audio-cpp/chatterbox-q8_0.gguf