feat(backends): add CUDA 13 + L4T arm64 CUDA 13 variants for vllm/vllm-omni/sglang (#9553)

* feat(backends): add CUDA 13 + L4T arm64 CUDA 13 variants for vllm/vllm-omni/sglang

Adds new build profiles mirroring the diffusers/ace-step pattern so vLLM
serving (and SGLang on arm64) can be deployed on CUDA 13 hosts and
JetPack 7 boards:

- vllm: cublas13 (PyPI cu130 channel) + l4t13 (jetson-ai-lab SBSA cu130
  prebuilt vllm + flash-attn).
- vllm-omni: cublas13 + l4t13. Floats vllm version on cu13 since vllm
  0.19+ ships cu130 wheels by default and vllm-omni tracks vllm master;
  cu12 path keeps the 0.14.0 pin to avoid disturbing existing images.
- sglang: l4t13 arm64 only — uses the prebuilt sglang wheel from the
  jetson-ai-lab SBSA cu130 index, so no source build is needed.
  Cublas13 sglang on x86_64 is intentionally deferred.

CI matrix gains five new images (-gpu-nvidia-cuda-13-vllm{,-omni},
-nvidia-l4t-cuda-13-arm64-{vllm,vllm-omni,sglang}); backend/index.yaml
gains the matching capability keys (nvidia-cuda-13, nvidia-l4t-cuda-13)
and latest/development merge entries.

Assisted-by: Claude:claude-opus-4-7 [Read] [Edit] [Write] [Bash]

* fix(backends): use unsafe-best-match index strategy on l4t13 builds

The jetson-ai-lab SBSA cu130 index lists transitive deps (decord, etc.)
at limited versions / older Python ABIs. uv defaults to the first index
that contains a package and refuses to fall through to PyPI, so sglang
l4t13 build fails resolving decord. Mirror the existing cpu sglang
profile by setting --index-strategy=unsafe-best-match on l4t13 across
the three backends, and apply it to the explicit vllm install line in
vllm-omni's install.sh (which doesn't honor EXTRA_PIP_INSTALL_FLAGS).

Assisted-by: Claude:claude-opus-4-7 [Read] [Edit] [Bash]

* fix(sglang): drop [all] extras on l4t13, floor version at 0.5.0

The [all] extra brings in outlines→decord, and decord has no aarch64
cp312 wheel on PyPI nor the jetson-ai-lab index (only legacy cp35-cp37
tags). With unsafe-best-match enabled, uv backtracked through sglang
versions trying to satisfy decord and silently landed on
sglang==0.1.16, an ancient version with an entirely different dep
tree (cloudpickle/outlines 0.0.44, etc.).

Drop [all] so decord is no longer required, and floor sglang at 0.5.0
to prevent any future resolver misfire from degrading the version
again.

Assisted-by: Claude:claude-opus-4-7 [Read] [Edit] [Bash]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

backend/python/sglang/install.sh

@@ -23,6 +23,19 @@ if [ "x${BUILD_PROFILE}" == "xcpu" ]; then
     EXTRA_PIP_INSTALL_FLAGS+=" --index-strategy=unsafe-best-match"
 fi
 
+# JetPack 7 / L4T arm64 wheels are built for cp312 and shipped via
+# pypi.jetson-ai-lab.io. Bump the venv Python so the prebuilt sglang
+# wheel resolves cleanly. unsafe-best-match is required because the
+# jetson-ai-lab index lists transitive deps (e.g. decord) at older
+# versions only — without it uv refuses to fall through to PyPI for a
+# compatible wheel and resolution fails.
+if [ "x${BUILD_PROFILE}" == "xl4t13" ]; then
+    PYTHON_VERSION="3.12"
+    PYTHON_PATCH="12"
+    PY_STANDALONE_TAG="20251120"
+    EXTRA_PIP_INSTALL_FLAGS+=" --index-strategy=unsafe-best-match"
+fi
+
 # sglang's CPU path has no prebuilt wheel on PyPI — upstream publishes
 # a separate pyproject_cpu.toml that must be swapped in before `pip install`.
 # Reference: docker/xeon.Dockerfile in the sglang upstream repo.