🔧 refactor(auth, channel, context): improve context setup and validation for multi-key channels

constant/multi_key_mode.go

@@ -0,0 +1,8 @@
+package constant
+
+type MultiKeyMode string
+
+const (
+	MultiKeyModeRandom  MultiKeyMode = "random"  // 随机
+	MultiKeyModePolling MultiKeyMode = "polling" // 轮询
+)