chore: import Local-Cursor v1.1.8 source snapshot

Includes the current working directory changes. Historical commits and release binaries are excluded to limit Gitea storage.
Source base: d7515973fbfd6dd2001fa156c483455b8081c7cb

internal/backend/server/policy.go

@@ -0,0 +1,19 @@
+package server
+
+type ExecutionMode string
+
+const (
+	// ModeLocal 表示本地模式，适用于直接处理请求的情况。
+	ModeLocal ExecutionMode = "local"
+	// ModeUpstream 表示直连上游模式，适用于将请求转发到原始地址。
+	ModeUpstream ExecutionMode = "upstream"
+)
+
+func parseExecutionMode(value string) ExecutionMode {
+	switch value {
+	case string(ModeUpstream):
+		return ModeUpstream
+	default:
+		return ModeLocal
+	}
+}