ci: switch sglang to prebuilt PyPI wheels (v0.5.11)

[kajalj22]

Summary

• Upgrade sglang 0.5.10 → 0.5.11 and sglang-kernel 0.4.1 → 0.4.2, switching from source builds to prebuilt PyPI wheels
• Eliminates the slow sglang-kernel CUDA compilation during Docker builds
• Possible because sglang v0.5.11 declares torch==2.11.0, matching our torch pin after the vLLM 0.20.0 upgrade in chore: Upgrade vLLM from 0.17.1 to 0.20.0 #2384 (now merged)

Dependency changes (pyproject.toml)

• Pinned sglang==0.5.11 and sglang-kernel==0.4.2 as regular PyPI deps
• Removed VCS git source entries for sglang and sglang-kernel from [tool.uv.sources]
• Removed sglang-kernel from extra-build-variables, no-build-isolation-package, and extra-build-dependencies
• Removed manual [[tool.uv.dependency-metadata]] sections for sglang and sglang-kernel (uv reads metadata from PyPI directly)
• Updated override-dependencies comments (flashinfer now aligned between vllm and sglang at 0.6.8.post1)
• Regenerated uv.lock — scikit-build-core dropped, easydict/kernels added, torchao bumped 0.9.0 → 0.17.0

Port fix (sglang_worker.py)

• sglang v0.5.11 derives grpc_port = port + 10000 and validates <= 65535
• Added retry loop to cap the server port at 55535 so grpc_port stays valid

CI / test changes

• Removed SKIP_SGLANG_BUILD=1 from cicd-main.yml — sglang now installs from PyPI, no source compilation to skip
• Removed python -c "import sglang" guards from test scripts (reverts c45e889) — sglang is always installed

Risks / things to verify

• CUDA arch compatibility: PyPI sglang-kernel wheels should include sm_90a (Hopper) and sm_100a (Blackwell) — needs runtime validation
• transformers override: sglang v0.5.11 declares transformers==5.6.0 but our override forces 5.3.0 — needs functional testing
• xgrammar override: sglang v0.5.11 wants 0.1.32, we override to 0.1.33 for CVE fix
• torchao bump: sglang v0.5.11 pulls in torchao==0.17.0 (up from 0.9.0) — verify no regressions

Test plan

• Build Docker image successfully (verify sglang-kernel installs from PyPI, no source compilation)
• Run sglang unit tests (test_sglang_non_divisible_batch_handling etc.)
• Run sglang functional/nightly tests (GRPO with sglang inference backend)

🤖 Generated with Claude Code

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[kajalj22]

/ok to test d702b90

[kajalj22]

/ok to test a0e27d8

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[kajalj22]

/ok to test b04b711

[kajalj22]

/ok to test 03cbabb