Improve crash reporting (#7728)

Many model crashes are masked behind "An existing connection was forcibly closed by the remote host"
This captures that common error message and wires in any detected errors from the log.

This also adds the deepseek context shift error to the known errors we capture.

llm/server.go

@@ -838,13 +838,15 @@ func (s *llmServer) Completion(ctx context.Context, req CompletionRequest, fn fu
 	}
 
 	if err := scanner.Err(); err != nil {
-		if strings.Contains(err.Error(), "unexpected EOF") {
+		if strings.Contains(err.Error(), "unexpected EOF") || strings.Contains(err.Error(), "forcibly closed") {
 			s.Close()
-			msg := ""
+			var msg string
 			if s.status != nil && s.status.LastErrMsg != "" {
 				msg = s.status.LastErrMsg
+			} else {
+				msg = err.Error()
 			}
-			return fmt.Errorf("an unknown error was encountered while running the model %s", msg)
+			return fmt.Errorf("an error was encountered while running the model: %s", msg)
 		}
 
 		return fmt.Errorf("error reading llm response: %v", err)

llm/status.go

@@ -27,6 +27,7 @@ var errorPrefixes = []string{
 	"\"ERR\"",
 	"error loading model",
 	"GGML_ASSERT",
+	"Deepseek2 does not support K-shift",
 }
 
 func (w *StatusWriter) Write(b []byte) (int, error) {