feat(translator): add built-in translator registry and helpers

- Introduced `builtin` package exposing a default registry and pipeline for built-in translators.
- Added format constants for common schemas (e.g., OpenAI, Gemini, Codex).
- Implemented helper functions for schema translation using format name strings.
- Provided example usage for integration with translator helpers.

sdk/translator/builtin/builtin.go

@@ -0,0 +1,18 @@
+// Package builtin exposes the built-in translator registrations for SDK users.
+package builtin
+
+import (
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+
+	_ "github.com/router-for-me/CLIProxyAPI/v6/internal/translator"
+)
+
+// Registry exposes the default registry populated with all built-in translators.
+func Registry() *sdktranslator.Registry {
+	return sdktranslator.Default()
+}
+
+// Pipeline returns a pipeline that already contains the built-in translators.
+func Pipeline() *sdktranslator.Pipeline {
+	return sdktranslator.NewPipeline(sdktranslator.Default())
+}

sdk/translator/formats.go

@@ -0,0 +1,11 @@
+package translator
+
+// Common format identifiers exposed for SDK users.
+const (
+	FormatOpenAI         Format = "openai"
+	FormatOpenAIResponse Format = "openai-response"
+	FormatClaude         Format = "claude"
+	FormatGemini         Format = "gemini"
+	FormatGeminiCLI      Format = "gemini-cli"
+	FormatCodex          Format = "codex"
+)

sdk/translator/helpers.go

@@ -0,0 +1,28 @@
+package translator
+
+import "context"
+
+// TranslateRequestByFormatName converts a request payload between schemas by their string identifiers.
+func TranslateRequestByFormatName(from, to Format, model string, rawJSON []byte, stream bool) []byte {
+	return TranslateRequest(from, to, model, rawJSON, stream)
+}
+
+// HasResponseTransformerByFormatName reports whether a response translator exists between two schemas.
+func HasResponseTransformerByFormatName(from, to Format) bool {
+	return HasResponseTransformer(from, to)
+}
+
+// TranslateStreamByFormatName converts streaming responses between schemas by their string identifiers.
+func TranslateStreamByFormatName(ctx context.Context, from, to Format, model string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, param *any) []string {
+	return TranslateStream(ctx, from, to, model, originalRequestRawJSON, requestRawJSON, rawJSON, param)
+}
+
+// TranslateNonStreamByFormatName converts non-streaming responses between schemas by their string identifiers.
+func TranslateNonStreamByFormatName(ctx context.Context, from, to Format, model string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, param *any) string {
+	return TranslateNonStream(ctx, from, to, model, originalRequestRawJSON, requestRawJSON, rawJSON, param)
+}
+
+// TranslateTokenCountByFormatName converts token counts between schemas by their string identifiers.
+func TranslateTokenCountByFormatName(ctx context.Context, from, to Format, count int64, rawJSON []byte) string {
+	return TranslateTokenCount(ctx, from, to, count, rawJSON)
+}