feat(audio-cpp): add ROCm backend image

The pinned audio.cpp revision supports HIP, but LocalAI neither builds a ROCm image nor accepts its backend option. AMD hosts therefore fall back to the CPU image.

Build and publish the HIP variant, connect it to AMD capability selection, and accept both upstream HIP names.

Assisted-by: Codex:gpt-5
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

backend/cpp/audio-cpp/model_options.cpp

@@ -59,6 +59,12 @@ bool starts_with(const std::string &value, const std::string &prefix) {
            value.compare(0, prefix.size(), prefix) == 0;
 }
 
+bool is_known_backend(const std::string &value) {
+    return value == "cpu" || value == "cuda" || value == "hip" ||
+           value == "rocm" || value == "vulkan" || value == "metal" ||
+           value == "best";
+}
+
 } // namespace
 
 ParsedOptions parse_model_options(const std::vector<std::string> &entries) {
@@ -107,6 +113,12 @@ ParsedOptions parse_model_options(const std::vector<std::string> &entries) {
         } else if (key == "task") {
             parsed.options.task = value;
         } else if (key == "backend") {
+            if (!is_known_backend(value)) {
+                parsed.error = "audio-cpp: unknown backend option '" + value +
+                               "'. Known backends: cpu, cuda, hip, rocm, "
+                               "vulkan, metal, best";
+                return parsed;
+            }
             parsed.options.backend = value;
         } else if (key == "model_spec_override") {
             parsed.options.model_spec_override = value;