feat: configurable tool pricing, Sub2API channel, and alpha search billing

Add admin-configurable tool-call prices with cross-provider surcharge
settlement, Sub2API channel support, /v1/alpha/search relay, and usage-log
surcharge UI.

router/relay-router.go

@@ -105,6 +105,11 @@ func SetRelayRouter(router *gin.Engine) {
 			controller.Relay(c, types.RelayFormatOpenAIResponsesCompaction)
 		})
 
+		// alpha search related routes (Codex standalone web search)
+		httpRouter.POST("/alpha/search", func(c *gin.Context) {
+			controller.Relay(c, types.RelayFormatOpenAIAlphaSearch)
+		})
+
 		// image related routes
 		httpRouter.POST("/edits", func(c *gin.Context) {
 			controller.Relay(c, types.RelayFormatOpenAIImage)