feat(api): 补齐资源分发服务入口

新增 bat-api 资源 bootstrap/分发 HTTP 服务、RPC release 发现、CDN path 分发、launcher 资源引导兼容、控制面中间件、OpenAPI 和 systemd 模板。

同步 Go 边界文档，明确 Rust bat 是资源生产者和同步运维入口，Go bat-api 是只读 bootstrap/分发服务，试验 Go CLI 产物为 bin/bat-go。

验证：未运行新命令；本轮已按要求停止重复构建/测试。

cmd/bat/main.go

@@ -34,10 +34,15 @@ func main() {
 }
 
 func printUsage() {
-	fmt.Println("bat - BlueArchiveToolkit CLI")
+	fmt.Println("bat-go - experimental Go helper (NOT the product CLI)")
+	fmt.Println()
+	fmt.Println("Product sync/ops CLI is the Rust binary `bat` (nearly fully automatic).")
+	fmt.Println("Product resource HTTP service is `bat-api` (see docs/reports/GO_STATUS.md).")
+	fmt.Println()
+	fmt.Println("This binary is experimental FFI demos only. Build output must be bin/bat-go.")
 	fmt.Println()
 	fmt.Println("Usage:")
-	fmt.Println("  bat doctor")
-	fmt.Println("  bat manifest inspect <file>")
-	fmt.Println("  bat sync plan <current-json> [previous-json]")
+	fmt.Println("  bat-go doctor")
+	fmt.Println("  bat-go manifest inspect <file>")
+	fmt.Println("  bat-go sync plan <current-json> [previous-json]")
 }