feat(translators): add token counting support for Claude and Gemini responses

- Implemented `TokenCount` transform method across translators to calculate token usage.
- Integrated token counting logic into executor pipelines for Claude, Gemini, and CLI translators.
- Added corresponding API endpoints and handlers (`/messages/count_tokens`) for token usage retrieval.
- Enhanced translation registry to support `TokenCount` functionality alongside existing response types.

internal/translator/claude/gemini-cli/claude_gemini-cli_response.go

@@ -54,5 +54,8 @@ func ConvertClaudeResponseToGeminiCLINonStream(ctx context.Context, modelName st
 	json := `{"response": {}}`
 	strJSON, _ = sjson.SetRaw(json, "response", strJSON)
 	return strJSON
-
+}
+
+func GeminiCLITokenCount(ctx context.Context, count int64) string {
+	return GeminiTokenCount(ctx, count)
 }