[Sync] Upstream V1 engine core — 89 PRs (bugfix, scheduler, runner, worker, hardware)

[MingqiWang-coder]

Purpose

Sync 89 upstream PRs from vllm-project/vllm main covering
V1 engine core bugfixes, scheduler, model runner, worker, compilation, and hardware-specific fixes.

Batch 1: bugfix / regression (62 PRs)

Security fixes (4): vllm-project#43286 vllm-project#44744 vllm-project#45118 vllm-project#45252
Bugfixes (56): vllm-project#35536 vllm-project#36616 vllm-project#38895 vllm-project#39155 vllm-project#39324 vllm-project#39562 vllm-project#39805 vllm-project#40398 vllm-project#40726 vllm-project#40727
vllm-project#40737 vllm-project#40749 vllm-project#40961 vllm-project#41119 vllm-project#41133 vllm-project#41233 vllm-project#41237 vllm-project#41411 vllm-project#41496 vllm-project#41549 vllm-project#41674 vllm-project#41873
vllm-project#41895 vllm-project#42040 vllm-project#42112 vllm-project#42289 vllm-project#42479 vllm-project#42585 vllm-project#42692 vllm-project#42706 vllm-project#42709 vllm-project#42739 vllm-project#42967 vllm-project#43001
vllm-project#43079 vllm-project#43125 vllm-project#43160 vllm-project#43616 vllm-project#43669 vllm-project#43719 vllm-project#43768 vllm-project#43808 vllm-project#43961 vllm-project#43982 vllm-project#43988 vllm-project#43998
vllm-project#44057 vllm-project#44560 vllm-project#44574 vllm-project#44744 vllm-project#45195 vllm-project#45345 vllm-project#45383 vllm-project#45487 vllm-project#45564 vllm-project#45673
Runner fixes (2): vllm-project#44568 vllm-project#44603

Batch 2: scheduler / engine core (10 PRs)

vllm-project#40984 vllm-project#44165 vllm-project#44594 vllm-project#44558 vllm-project#42187 vllm-project#42288 vllm-project#42938 vllm-project#44212 vllm-project#43689 vllm-project#42313

Batch 3: runner / worker / compilation (12 PRs)

vllm-project#40451 vllm-project#35520 vllm-project#41882 vllm-project#40392 vllm-project#42604 vllm-project#43746 vllm-project#41714 vllm-project#40470 vllm-project#45163 vllm-project#45473 vllm-project#45868 vllm-project#44635

Hardware extras (5 PRs)

vllm-project#41972 vllm-project#41771 vllm-project#43016 vllm-project#40082 vllm-project#43781

Test Plan

# Unit tests
pytest test_scheduler.py -q          # 107 passed
pytest test_xgrammar_backend.py -q  # 7 passed
pytest test_utils.py -q  # 6 passed

# Syntax check
python -m compileall vllm/                          # all clean

# End-to-end inference (Ascend NPU)
python -c "
from vllm import LLM
llm = LLM(model='facebook/opt-125m', max_model_len=128, enforce_eager=True, gpu_memory_utilization=0.5)
output = llm.generate('Hello, my name is')
print(output[0].outputs[0].text)
"
# → "Johntox, and I'm from the UK."

## Test Result

---
<details>
<summary> Essential Elements of an Effective PR Description Checklist </summary>

- [ ] The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
- [ ] The test plan, such as providing test command.
- [ ] The test results, such as pasting the results comparison before and after, or e2e results
- [ ] (Optional) The necessary documentation update, such as updating `supported_models.md` and `examples` for a new model.
</details>

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[github-actions]

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[github-actions]

Ascend Benchmark Result

• Commit: 8afdaa3f9bf848cb7bfdbd43b19c3fdb90afd6c4
• Scenario: random-online
• Model: Qwen/Qwen2.5-3B-Instruct
• Publish mode: artifact-preview
• Leaderboard publish: skipped
• HF publish: skipped
• Perfgate mode: report
• Baseline source: unavailable
• Scenario mode: unavailable
• Scenario label: none
• Scenario reason: unavailable
• Workflow run: view run
• Raw benchmark result: missing
• Leaderboard entry: missing
• Note: random-online runs stay as preview artifacts unless random preview publish is explicitly enabled.