fix(mcp): include wikitext in the mcp extra, streamline tools docs

[LukasGold]

Changes

Packaging

• pyproject.toml: the mcp extra now requires osw[wikitext], so mwparserfromhell is installed with every MCP install. uv.lock updated accordingly.

docs/tools/index.md

• Setup now shows one install route, uv tool install "osw[mcp]", with a note on the tool bin directory, uv tool update-shell and quoting the brackets for zsh.
• pip install, uv add and uvx moved into a collapsed "Other ways to install" block.
• Editable install guidance removed from this page and moved to the developer notes in mcp.md.

docs/tools/mcp.md

• New sentence after the intro: a registered server either runs uvx or an installed osw[mcp], with a link to the decision section.
• "uvx or the installed command" renamed to "Which command to register for the MCP server" and rewritten as two bullets, one per option, each with its cost.
• The installed-command option now shows the full claude mcp add ... -- osw-mcp entry and its JSON form.
• "Notes for developers" documents the editable uv tool install (uv tool install --reinstall --editable ".[mcp]"), its four consequences, and when to prefer uvx instead.
• Caveat added: uvx reuses an installed osw tool whenever that installation satisfies the specification, so an unpinned osw[mcp] runs the installed version.

Rationale

• The wikitext warning from src/osw/wiki_tools.py appeared on the MCP server's stderr at import time and therefore in every client log. The extra now satisfies the dependency instead of silencing the message.
• uv tool install "osw[mcp]" puts osw-mcp on PATH, so a client entry can be "command": "osw-mcp" with an empty args array. Changing the version for all servers is then one uv tool upgrade osw, instead of editing every entry that names --from.
• The tools pages offered several install routes with no guidance on which to choose. There is now one visible path per page and a single place that explains the trade-off.

Verification

• uv run --isolated --no-project --with "osw[mcp]==2.6.2" python -c "import osw.mcp.server" prints the wikitext warning. The same command against this checkout does not.
• uv run --isolated --no-project --with "osw==2.6.2" osw-mcp fails with ModuleNotFoundError: No module named 'mcp' at osw/mcp/server.py:16, which is the behaviour described in index.md.
• uvx -v confirms the reuse caveat: an unpinned osw[mcp] reports Found existing environment for tool osw, while osw[mcp]==2.6.1 installs a fresh environment.
• uv run zensical build -s reports no issues. The anchor #which-command-to-register-for-the-mcp-server exists in the built HTML and the link from index.md resolves to it.

[github-actions]

Release preview

Merging this PR would release v2.6.3 (current: v2.6.2).

Changelog preview (truncated)

## v2.6.3 (2026-09-22)

### Bug Fixes

- **mcp**: Include the wikitext extra in the mcp extra
  ([`adf50d2`](https://github.com/OpenSemanticLab/osw-python/commit/adf50d21405cbc396491929c6faa54b3de1caf8d))

### Documentation

- **mcp**: Note that uvx reuses an installed osw tool
  ([`c492583`](https://github.com/OpenSemanticLab/osw-python/commit/c492583db6a7a19647a828881b7fd45992697c96))

- **tools**: Document uv tool install for osw and osw-mcp
  ([`d691ef4`](https://github.com/OpenSemanticLab/osw-python/commit/d691ef428eff2735cb92f6ad0ea55363b6361c2a))

- **tools**: Streamline install and registration guidance
  ([`ed18174`](https://github.com/OpenSemanticLab/osw-python/commit/ed1817465d1e9518c9903742276ce5a2352e8066))

_{Preview via python-semantic-release and conventional commits.}