[notforu777]

Brings atomic up to upstream master b13a482. The diff is upstream's 36 commits since 0963357; nothing in atomic/ or release-atomic.yml changes, and no file overlaps. The main reason is FLUX.3 Image Klein (leejet#2143, master-968-8cd731e). Atomic Chat cannot run Klein on the engine it ships now (master-883-137f740).

What the app needs from this repo: a release of master-975-95b3090 (or newer). Merging this PR does not change any build, because every build starts from an upstream tag.

Build check, not a release: Release (Atomic) is dispatched with upstream_tag=master-975-95b3090, targets=all, publish=false: https://github.com/AtomicBot-ai/stable-diffusion.cpp/actions/runs/39418844902

• atomic/patches/0001 still applies: it touches thirdparty/CMakeLists.txt, which upstream did not change.

Left for the app side:

1. Release (Atomic) with publish=true for the tag.
2. mirror-sdcpp.yml in atomic-chat-conf.
3. The manifest pin.
4. A Klein preset:
   • 16 steps, cfg 1.0, euler;
   • the default discrete schedule (shift 6.93), no custom sigmas;
   • the text encoder is a Qwen3-VL-4B GGUF passed as --llm; the VAE is the FLUX.2 one.
5. Klein expects full scene captions from a prompt upsampler (BFL's is a 9B Qwen3.5 model). Short prompts give generic images. The app has no upsampler step yet.

GGUF quants and quality numbers for Klein: in progress on AtomicChat's HF.

[notforu777]

The build-only run passed: https://github.com/AtomicBot-ai/stable-diffusion.cpp/actions/runs/39418844902

• Every target of master-975-95b3090 built and passed its smoke test, atomic/patches included.
• release was skipped on purpose (publish=false).

On our H100 box, upstream 95b3090 renders FLUX.3 Image Klein (16 steps, cfg 1, euler) in about 9 s at 1024². A second bf16 render matches the first to LPIPS 0.0004.

Next steps for the app: Release (Atomic) with publish=true, then mirror-sdcpp.yml, then the manifest pin.