config(extension): 配置WebSocket连接URL为构建时变量

- 移除DEFAULT_DAEMON_PORT常量定义
- 使用__BSK_DAEMON_WS_URL__构建时变量替代硬编码端口
- 在wxt.config.ts和vitest.config.ts中添加环境变量配置
- 为__BSK_DAEMON_WS_URL__添加类型声明和文档注释
- 默认值保持为ws://127.0.0.1:52800，可通过BSK_DAEMON_WS_URL环境变量覆盖

apps/extension/src/transport/build-info.d.ts

@@ -5,3 +5,10 @@
 // at runtime (review M3 fix to round-1).
 
 declare const __BSK_EXT_VERSION__: string;
+
+/**
+ * WebSocket URL the extension uses to connect to the local bsk daemon.
+ * Defaults to {@code ws://127.0.0.1:52800}. Override at build time by
+ * setting the {@code BSK_DAEMON_WS_URL} environment variable.
+ */
+declare const __BSK_DAEMON_WS_URL__: string;