refactor: split the repo into self-contained validator, directory, quickstart, spec and site folders

validator/ holds mewslint (lint, css, fetch, DTD/CSS data); directory/ holds
the mews.page service (app, db, check, pages, cli) and depends on validator/;
quickstart/ holds mews-quickstart and md2mews.py for third parties who want
to create Mews content without cloning the repo; spec/ consolidates doc/ and
dtd/ with the canonical mews-0.1.css; site/ becomes a Pelican project with
the forward-facing pages as Markdown, the check form kept as a raw HTML
snippet. Root pyproject.toml is now a virtual uv workspace over validator,
directory and quickstart, with cross-cutting tests that span more than one
of them staying at the repo root. Makefile and flake.nix updated to match.

site/theme/templates/page.html

@@ -0,0 +1,5 @@
+{% extends "base.html" %}
+{% block title %}{{ page.title }}{% endblock %}
+{% block content %}
+{{ page.content }}
+{% endblock %}