[anhnh2002]

Closes #145.

What

Adds Backstage TechDocs output, built on the generator proposed in the issue.

• codewiki generate --techdocs [--techdocs-dir DIR] (default ./techdocs) exports right after generation, like --github-pages.
• codewiki techdocs [DOCS_DIR] [OUT_DIR] exports existing docs without any LLM calls. Re-run it after --update.

The output is an MkDocs project that techdocs-cli generate builds as is:

techdocs/
├── mkdocs.yml   # techdocs-core, nav from the module tree, mermaid superfences
└── docs/
    ├── index.md # overview.md
    └── ...      # module pages in the same layout, plus images

Each page gets front matter (title/description), a provenance banner (commit, date, model) and a collapsible "Documented components" list linked to the source at the documented commit. The repository URL comes from git origin: SSH remotes become https and credentials are dropped. GitHub, GitLab and bitbucket.org links are built automatically, and --source-url-template covers other hosts. JSON files and temp/ are not published, and the source docs are never modified.

Changes from the script in the issue

• Re-runs: _prepare_out_docs was passed out/docs and appended docs again. Stale pages were never cleared and the marker file landed in docs/docs/.
• Nav check: whether a page was already in the nav was checked by splitting the YAML dump. It now walks the nav itself.
• Descriptions: a first paragraph starting with **bold** was skipped as a list item, and fenced code wasn't tracked.
• Titles: pages outside the module tree get their H1 as the nav title.
• Pre-flight check: generate --techdocs validates the output folder before the LLM run.
• Failures: a failed export after generation prints a warning and the retry command instead of failing the run.

Safety

• Only a docs/ folder created by an earlier export (it carries a marker file) is ever replaced.
• The output may not overlap the CodeWiki docs directory.

Docs

• New guides/backstage-techdocs.md covering the catalog annotation, building with techdocs-cli, and the Mermaid addon Backstage needs to render diagrams.
• Updated the README, guides/cli-reference.md and the CHANGELOG.

Testing

• tests/test_techdocs.py: 15 tests covering both layouts, link rewriting, the nav, banner and components, re-runs, the refusals, URL normalisation and the CLI.
• All tracked tests pass, and so does ruff.
• Exported this repo's own docs/ (35 pages) and built it with mkdocs build --strict using mkdocs-techdocs-core 1.7.1. It builds cleanly, and Mermaid, admonitions and the details blocks render.