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/base.html

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.2//EN"
+  "http://www.openmobilealliance.org/tech/DTD/xhtml-mobile12.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="{{ DEFAULT_LANG }}" lang="{{ DEFAULT_LANG }}">
+  <head>
+    <title>{% block title %}{{ SITENAME }}{% endblock %}</title>
+{% include "mews/head.html" %}
+{% if page.description %}    <meta name="description" content="{{ page.description }}" />
+{% endif %}  </head>
+  <body class="mews-cool">
+{% block content %}{% endblock %}
+  </body>
+</html>

site/theme/templates/page.html

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