fix(llama-cpp): explain tensor count mismatch

llama.cpp reports the same tensor-count error for unsupported model layouts and damaged GGUF files. Add a focused hint so operators can update the backend or verify the model without losing the upstream diagnostic.

Assisted-by: Codex:gpt-5.6
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

backend/cpp/llama-cpp/grpc-server.cpp

@@ -53,6 +53,7 @@
 #include "arg.h"
 #include "chat-auto-parser.h"
 #include "llama_compat.h" // fork-skew switches, generated by prepare.sh
+#include "model_load_error.h"
 #include "thread_params.h"
 #include "message_content.h"
 #include "passthrough_options.h"
@@ -1628,7 +1629,8 @@ public:
             {
                 std::lock_guard<std::mutex> lock(error_capture_data.error_mutex);
                 if (!error_capture_data.captured_error.empty()) {
-                    error_msg += ". Error: " + error_capture_data.captured_error;
+                    error_msg += ". Error: " +
+                                 localai::model_load_error_with_hint(error_capture_data.captured_error);
                 } else {
                     error_msg += ". Model file may not exist or be invalid.";
                 }