test: strengthen Jieli adapter follow-up coverage

[maidang-xing]

PR 描述/PR description

Extend the Jieli CI workflow for xb/tuyaopen-jl by preparing the pinned JIELI platform checkout and running the focused platform tests. Tighten build, config, flash-bridge, and UART hello regression coverage; update the AC791/AC792 guide to distinguish historical evidence from outstanding hardware acceptance; remove unrelated AI memory options from the switch_demo default config.

Validation: .venv\Scripts\python.exe -m unittest discover -s tests/platform -t . -p 'test_jieli_*.py' — 48 tests passed; git diff --check passed. GitHub runner execution is not yet verified. No real Jieli build or physical-board validation was performed for this PR.

代码质量/Code Quality:

在本次拉取请求中，我已考虑以下事项 As part of this pull request, I've considered the following:

• 确保代码注释和文档清晰，并使用英文注释以保证代码可读性。Ensure that code comments and documentation are clear, and use English comments for readability.
• 确保文件头遵循文件头格式。Ensure that file headers follow the File Header Format.
• 确保函数头遵循 Doxygen 格式。Ensure that function headers follow the Doxygen format.
• 已查阅 编码风格指南，并核查代码风格合规性，包括缩进、空格、命名规范及其他风格要求。Reviewed the Coding Style Guide for indentation, spacing, naming, and other style requirements.
• 已使用代码格式化工具确保符合 TuyaOpen 编码规范。Used the code-formatting tool to check TuyaOpen coding standards.