AI网关新增xAI格式TTS端点与过滤弃用模型开关

- POST /ai/v1/tts:xAI 官方 TTS 格式转换层(text/voice_id→input/voice),复用 Speech 编排,model 缺省 xai.grok-tts;实测 output_format/speed 透传生效
- 「过滤弃用模型」开关(GET/PUT /api/v1/ai-settings,settings 表持久化):开启后已宣布弃用(未退役)模型从列表与路由排除;同步入库与退役提醒不受影响
- AI 网关文档更名 docs/AI网关.md,补 tts 矩阵段与开关说明;README 引用同步
- CHANGELOG 0.5.0(0.4.0 已发版冻结);DASH_VERSION v0.5.0

internal/api/routes_ai.go

@@ -16,6 +16,7 @@ func registerAiGateway(r *gin.Engine, aiGateway *service.AiGatewayService) {
 	ai.POST("/messages", aih.messages)
 	ai.POST("/embeddings", aih.embeddings)
 	ai.POST("/audio/speech", aih.audioSpeech)
+	ai.POST("/tts", aih.tts)
 	ai.POST("/rerank", aih.rerank)
 	ai.POST("/moderations", aih.moderations)
 	ai.GET("/models", aih.listModels)
@@ -36,6 +37,8 @@ func registerAiAdmin(secured *gin.RouterGroup, aiGateway *service.AiGatewayServi
 	secured.POST("/ai-channels/:id/probe", aiadmin.probeChannel)
 	secured.POST("/ai-channels/:id/sync-models", aiadmin.syncChannelModels)
 	secured.GET("/ai-models", aiadmin.gatewayModels)
+	secured.GET("/ai-settings", aiadmin.aiSettings)
+	secured.PUT("/ai-settings", aiadmin.updateAiSettings)
 	secured.GET("/ai-blacklist", aiadmin.listBlacklist)
 	secured.POST("/ai-blacklist", aiadmin.addBlacklist)
 	secured.DELETE("/ai-blacklist/:id", aiadmin.removeBlacklist)