docs(rock3b): unify download page OS section format

- Rename section headers: 官方操作系统镜像 → 瑞莎系统, 第三方操作系统镜像 → 第三方系统
- Rename English: Official Operating System Image → Radxa System, Third-Party Operating System images → Third-Party System
- Remove <Images> component and unused import, use direct markdown links instead
- Both Debian Bullseye b18 and Bookworm KDE R1 listed as direct links

Author: tangzz-radxa

docs/rock3/rock3b/download.md

@@ -2,23 +2,20 @@
 sidebar_position: 2
 ---
 
-import Images from "./\_image.mdx"
-
 # 资源下载汇总
 
 ## 操作系统镜像
 
-### 官方操作系统镜像
-
-<Images loader={false} system_img={true} spi_img={false} />
+### 瑞莎系统
 
-- [Rock-3b Bookworm KDE R1](https://github.com/radxa-build/rock-3b/releases/download/rsdk-r1/rock-3b_bookworm_kde_r1.output_512.img.xz)(适用于 microSD 卡和 eMMC 模块启动系统)
+- [Rock-3b Debian Bullseye XFCE b18](https://github.com/radxa-build/rock-3b/releases/download/b18/rock-3b_debian_bullseye_xfce_b18.img.xz)
+- [Rock-3b Bookworm KDE R1](https://github.com/radxa-build/rock-3b/releases/download/rsdk-r1/rock-3b_bookworm_kde_r1.output_512.img.xz)
 
 :::caution
 除了上面的镜像经过官方充分测试外，其他镜像未经过严格测试，可能会存在未知问题，仅用于评估使用。
 :::
 
-### 第三方操作系统镜像
+### 第三方系统
 
 - [Radxa ROCK 3B OpenWrt](https://openwrt.org/toh/hwdata/radxa/radxa_rock_3b)
 - [Radxa ROCK 3B OpenWrt ext4 sysupgrade 镜像](https://downloads.openwrt.org/releases/25.12.0/targets/rockchip/armv8/openwrt-25.12.0-rockchip-armv8-radxa_rock-3b-ext4-sysupgrade.img.gz)

i18n/en/docusaurus-plugin-content-docs/current/rock3/rock3b/download.md

@@ -2,23 +2,20 @@
 sidebar_position: 2
 ---
 
-import Images from "./\_image.mdx"
-
 # Summary of resource downloads
 
 ## Operating system image
 
-### Official Operating System Image
-
-<Images loader={false} system_img={true} spi_img={false} />
+### Radxa System
 
-- [Rock-3b Bookworm KDE R1](https://github.com/radxa-build/rock-3b/releases/download/rsdk-r1/rock-3b_bookworm_kde_r1.output_512.img.xz)(For booting from microSD card and eMMC module)
+- [Rock-3b Debian Bullseye XFCE b18](https://github.com/radxa-build/rock-3b/releases/download/b18/rock-3b_debian_bullseye_xfce_b18.img.xz)
+- [Rock-3b Bookworm KDE R1](https://github.com/radxa-build/rock-3b/releases/download/rsdk-r1/rock-3b_bookworm_kde_r1.output_512.img.xz)
 
 :::caution
 Except for the above mirrors which have been fully tested officially, the other mirrors have not been rigorously tested and may have unknown issues and are for evaluation purposes only.
 :::
 
-### Third-Party Operating System images
+### Third-Party System
 
 - [Radxa ROCK 3B OpenWrt](https://openwrt.org/toh/hwdata/radxa/radxa_rock_3b)
 - [Radxa ROCK 3B OpenWrt ext4 sysupgrade image](https://downloads.openwrt.org/releases/25.12.0/targets/rockchip/armv8/openwrt-25.12.0-rockchip-armv8-radxa_rock-3b-ext4-sysupgrade.img.gz)