Doc: refresh Galactic-center reference image and benchmark links

Replace the artifact-affected Schwarzschild image with the corrected 4K render. Link both READMEs to the paired CPU/HIP benchmark and clarify that this run had no PSF wing clipping or direct fallbacks.

README.md

@@ -122,11 +122,12 @@ mkdir -p output/imgs
   --output output/imgs/schwarzschild_galactic_center.png
 ```
 
-This uses the reference image's rendering settings, including its
+This uses the updated reference image's rendering settings. The
-`--max-cache-psf-flux 1e8` preview approximation, which clips bright PSF wings
+`--max-cache-psf-flux 1e8` setting permits bright PSF wings to be clipped to the
-to the cache radius. The [original benchmark record](benchmarks/2mass_galactic_center_blackhole.md)
+cache radius, but this run reported no wing clipping or direct fallbacks.
-preserves the command and terminal output; the command above omits the optional
+The [CPU/HIP benchmark record](benchmarks/2mass_galactic_center_cpu_hip_2026-09-07.md)
-HDR export.
+preserves the commands and terminal output, and records bit-identical CPU/HIP
+PNGs. The command above omits the optional HDR and lens-map exports.
 
 This example infers a position facing the hole from its look direction and radius. Adaptive refinement should
 be configured for the desired image accuracy; it is disabled by default.

README.zh-CN.md

@@ -82,7 +82,7 @@ mkdir -p output/imgs
   --output output/imgs/schwarzschild_galactic_center.png
 ```
 
-这里使用参考图像的渲染设置，包括 `--max-cache-psf-flux 1e8` 这一预览近似：它将明亮 PSF 的翼部截断在缓存半径内。[原始 benchmark 记录](benchmarks/2mass_galactic_center_blackhole.md)保留了命令与终端输出；上述命令省略了可选的 HDR 导出。
+这里使用更新后的参考图像的渲染设置。`--max-cache-psf-flux 1e8` 允许将明亮 PSF 的翼部截断在缓存半径内，但本次运行没有发生翼部裁剪或 direct fallback。[CPU/HIP benchmark 记录](benchmarks/2mass_galactic_center_cpu_hip_2026-09-07.md)保留了命令、终端输出，以及 CPU/HIP PNG 比特级一致的结果；上述命令省略了可选的 HDR 和 lens-map 导出。
 
 上述 Schwarzschild 示例省略位置，因此按指向与半径推导出朝向黑洞的相机。自适应细分默认关闭，应根据所需图像精度配置。相机控制、图像序列、透镜映射复用、PSF 设置及 HDR 输出参见 [usage.md](usage.md)（英文）。两个可执行文件都可通过 `--help` 查看完整选项。