AI网关新增TTS/重排/审核端点,xAI工具扩展,swagger修缺

- 新端点 /ai/v1/audio/speech(xai.grok-tts)、/rerank(cohere.rerank-v4)、/moderations(OCI Guardrails)
- Responses 放行 code_interpreter 与远程 mcp 工具,web_search/x_search 解除仅非流式限制
- 模型能力映射扩展:TEXT_RERANK→RERANK、TEXT_TO_AUDIO→TTS
- AI 网关文档独立 docs/ai-gateway.md,字段兼容矩阵只列支持项;README 精简引用
- swagger 修缺:135 处响应注解具体化,RawMessage/联合类型统一渲染 AnyJSON,overrides 迁至 docs/.swaggo
- CHANGELOG 0.4.0,版本段不再记日期;DASH_VERSION v0.4.0

internal/api/aigateway_test.go

@@ -95,6 +95,14 @@ func TestAiGatewayKeyModelRestrict(t *testing.T) {
 		{"chat completions 不支持内容块拒绝", "open-key-12345", "/ai/v1/chat/completions",
 			`{"model":"ghost-model","messages":[{"role":"user","content":[{"type":"input_audio"}]}]}`,
 			400, []string{"invalid_request_error"}},
+		{"audio speech 白名单外拦截", "limited-key-1234", "/ai/v1/audio/speech",
+			`{"model":"meta.llama-3.3-70b-instruct","input":"你好"}`, 404, deny},
+		{"rerank 白名单外拦截", "limited-key-1234", "/ai/v1/rerank",
+			`{"model":"meta.llama-3.3-70b-instruct","query":"q","documents":["d"]}`, 404, deny},
+		{"rerank 缺 documents 拒绝", "open-key-12345", "/ai/v1/rerank",
+			`{"model":"ghost-model","query":"q"}`, 400, []string{"invalid_request_error"}},
+		{"moderations 空 input 拒绝", "open-key-12345", "/ai/v1/moderations",
+			`{"input":[]}`, 400, []string{"invalid_request_error"}},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {