v4.29.0 — the last manual install step is gone

Added — the last manual install step is gone

Installing pandoc was the one thing left that a user had to do by hand, and
skipping it does not fail loudly: the renderer falls back to python-docx and
delivers a document with no real Word tables and none of the template's layout.
A first-time reader does not experience that as a missing dependency. They
experience it as a tool that produces mediocre documents.

• pip install "report-workflow[render]" carries pandoc in the wheel.
  pypandoc-binary ships the binary per platform, and _find_pandoc now looks
  there after the PATH and the known Windows install locations. A system pandoc
  still wins — it is the one the user chose, and it is usually newer. Kept an
  extra rather than a dependency: those wheels cover win_amd64, macOS
  x86_64/arm64 and manylinux/musllinux, so a core dependency would make
  pip install report-workflow fail everywhere else.
• The plugin asks for both extras. Its server command is now
  uvx --from "report-workflow[mcp,render]" report-workflow-mcp, so installing
  the plugin gets full-fidelity rendering with nothing installed by hand. The
  cost is a larger first run while uvx fetches the binary; it is cached after
  that.

Verified in a clean uv environment built from this commit: with only the
render extra, _bundled_pandoc() resolves to the binary inside the installed
pypandoc package.