refactor: replace sjson.Set usage with sjson.SetBytes to optimize mutable JSON transformations

internal/translator/common/bytes.go

@@ -0,0 +1,67 @@
+package common
+
+import (
+	"strconv"
+
+	"github.com/tidwall/sjson"
+)
+
+func WrapGeminiCLIResponse(response []byte) []byte {
+	out, err := sjson.SetRawBytes([]byte(`{"response":{}}`), "response", response)
+	if err != nil {
+		return response
+	}
+	return out
+}
+
+func GeminiTokenCountJSON(count int64) []byte {
+	out := make([]byte, 0, 96)
+	out = append(out, `{"totalTokens":`...)
+	out = strconv.AppendInt(out, count, 10)
+	out = append(out, `,"promptTokensDetails":[{"modality":"TEXT","tokenCount":`...)
+	out = strconv.AppendInt(out, count, 10)
+	out = append(out, `}]}`...)
+	return out
+}
+
+func ClaudeInputTokensJSON(count int64) []byte {
+	out := make([]byte, 0, 32)
+	out = append(out, `{"input_tokens":`...)
+	out = strconv.AppendInt(out, count, 10)
+	out = append(out, '}')
+	return out
+}
+
+func SSEEventData(event string, payload []byte) []byte {
+	out := make([]byte, 0, len(event)+len(payload)+14)
+	out = append(out, "event: "...)
+	out = append(out, event...)
+	out = append(out, '\n')
+	out = append(out, "data: "...)
+	out = append(out, payload...)
+	return out
+}
+
+func AppendSSEEventString(out []byte, event, payload string, trailingNewlines int) []byte {
+	out = append(out, "event: "...)
+	out = append(out, event...)
+	out = append(out, '\n')
+	out = append(out, "data: "...)
+	out = append(out, payload...)
+	for i := 0; i < trailingNewlines; i++ {
+		out = append(out, '\n')
+	}
+	return out
+}
+
+func AppendSSEEventBytes(out []byte, event string, payload []byte, trailingNewlines int) []byte {
+	out = append(out, "event: "...)
+	out = append(out, event...)
+	out = append(out, '\n')
+	out = append(out, "data: "...)
+	out = append(out, payload...)
+	for i := 0; i < trailingNewlines; i++ {
+		out = append(out, '\n')
+	}
+	return out
+}