fix(kokoros): add missing animate3_d stub to Backend trait impl (#12301)

* fix(kokoros): add missing animate3_d stub to Backend trait impl

#12095 added the Animate3D RPC to backend.proto, but the kokoros
service never got a matching method. The tonic-generated Backend trait
now requires it, so kokoros fails to build with E0046 whenever the
full backend matrix runs.

Return Unimplemented, as the other unsupported RPCs do.

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

* fix(kokoros): fill new Result fields with defaults

backend.proto added a metadata field to Result, so the struct literals
in the kokoros service no longer name every field and fail to compile.
Spread Default::default() into them, so later additive proto fields do
not break the build again.

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

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>

backend/rust/kokoros/src/service.rs

@@ -132,6 +132,7 @@ impl Backend for KokorosService {
         Ok(Response::new(backend::Result {
             success: true,
             message: "Kokoros TTS model loaded".into(),
+            ..Default::default()
         }))
     }
 
@@ -180,11 +181,13 @@ impl Backend for KokorosService {
                     return Ok(Response::new(backend::Result {
                         success: false,
                         message: format!("Failed to write WAV: {}", e),
+                        ..Default::default()
                     }));
                 }
                 Ok(Response::new(backend::Result {
                     success: true,
                     message: String::new(),
+                    ..Default::default()
                 }))
             }
             Err(e) => {
@@ -192,6 +195,7 @@ impl Backend for KokorosService {
                 Ok(Response::new(backend::Result {
                     success: false,
                     message: format!("TTS error: {}", e),
+                    ..Default::default()
                 }))
             }
         }
@@ -292,6 +296,7 @@ impl Backend for KokorosService {
         Ok(Response::new(backend::Result {
             success: true,
             message: "Model freed".into(),
+            ..Default::default()
         }))
     }
 
@@ -348,6 +353,13 @@ impl Backend for KokorosService {
         Err(Status::unimplemented("Not supported"))
     }
 
+    async fn animate3_d(
+        &self,
+        _: Request<backend::Animate3DRequest>,
+    ) -> Result<Response<backend::Result>, Status> {
+        Err(Status::unimplemented("Not supported"))
+    }
+
     async fn audio_transcription(
         &self,
         _: Request<backend::TranscriptRequest>,