docs: add generated OpenWiki code documentation

[ngadminq]

What changed

Describe the focused change and the part of the RAG pipeline it affects.

Why

Explain the bug, learning need, maintenance requirement, or user impact.

Validation

• python -m compileall -q api_router.py config.py rag_demo.py version.py core features utils tests
• PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 python -m pytest
• Relevant UI or API path checked when applicable
• No API keys, private documents, personal data, or generated model files included
• Chinese and English documentation updated when public behavior changed

Related issues

Closes #

[weiwill88]

Thanks for the contribution. I am requesting changes before this generated documentation can be merged.

The current PR adds 24 Markdown files and 5,815 lines, but the generated output is not yet review-ready:

1. The PR description is still the unfilled template, and none of the validation items are checked.
2. The openwiki/ tree contains 76 openwiki: broken internal link diagnostics. Many links start at the repository root (for example, /core/...) even though the targets live under openwiki/.
3. openwiki/architecture/overview.md still contains a Mermaid parse-failure diagnostic and renders the architecture diagram as a text block.
4. openwiki/configuration/environment-and-models.md documents the configuration precedence incorrectly. load_dotenv() uses override=False by default, so an existing process environment value wins over the dotenv file; the code also chooses either .env or example.env, rather than loading both as successive priority layers.
5. The hard-coded coverage estimates in openwiki/testing/overview.md are not reproducible and disagree with the current test run. Generated documentation should not publish approximate coverage figures unless they are produced from CI artifacts.
6. The PR does not explain how this large generated documentation set will be regenerated, validated, or kept synchronized with source changes. Passing the existing Python tests does not validate Markdown links, diagrams, or factual accuracy.

Please address the following before requesting another review:

• Remove all generator diagnostic comments and make the internal links and Mermaid diagrams pass validation.
• Correct source-grounded statements and remove or automatically generate unstable metrics such as coverage.
• Document the regeneration command/tool version and the expected maintainer workflow.
• Complete the PR description and validation checklist.
• Squash the generated revisions into a clean update after validation.

I am leaving the PR open so it can be revised.