[CICD] Add Hygon BW1000 CI support

[hooray03]

What

• add a Hygon BW1000 training image based on the documented DTK 26.04 base image
• add Hygon vendor configuration for the flagscale-hygon-bw1000-gpu8 runner
• run Qwen3 0.6B training against the real Nemotron dataset and Qwen tokenizer
• separate vendor image construction from normal tests through a reusable build workflow
• scope image build triggers to vendor Docker, install, requirements, config, and workflow files

Validation

• Hygon training stack imports passed manually on 8 BW1000 devices
• two-rank FlagCX all-reduce passed manually
• Qwen3 0.6B real-data two-iteration smoke training completed and saved a checkpoint
• pre-commit passed

Pending

• CI must complete on the Hygon runner
• record Golden Loss only from a successful deterministic 10-iteration real-data CI run
• commits intentionally remain unsquashed until CI is fully green

[CLAassistant]

All committers have signed the CLA.