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.

uv.lock

@@ -2,6 +2,23 @@ version = 1
 revision = 3
 requires-python = ">=3.12"
 
+[manifest]
+members = [
+    "mews",
+    "mews-directory",
+    "mews-quickstart",
+]
+
+[manifest.dependency-groups]
+dev = [
+    { name = "mews", editable = "validator" },
+    { name = "mews-directory", editable = "directory" },
+    { name = "mews-quickstart", editable = "quickstart" },
+    { name = "mistune", specifier = ">=3.0" },
+    { name = "pytest", specifier = ">=8.0" },
+    { name = "ruff", specifier = ">=0.15" },
+]
+
 [[package]]
 name = "anyio"
 version = "4.15.1"
@@ -201,19 +218,16 @@ wheels = [
 [[package]]
 name = "mews"
 version = "0.1.0"
-source = { editable = "." }
+source = { editable = "validator" }
 dependencies = [
     { name = "httpx" },
     { name = "lxml" },
     { name = "publicsuffixlist" },
-    { name = "waitress" },
 ]
 
 [package.dev-dependencies]
 dev = [
-    { name = "mistune" },
     { name = "pytest" },
-    { name = "ruff" },
 ]
 
 [package.metadata]
@@ -221,15 +235,38 @@ requires-dist = [
     { name = "httpx", specifier = ">=0.27" },
     { name = "lxml", specifier = ">=5.0" },
     { name = "publicsuffixlist", specifier = ">=0.10" },
+]
+
+[package.metadata.requires-dev]
+dev = [{ name = "pytest", specifier = ">=8.0" }]
+
+[[package]]
+name = "mews-directory"
+version = "0.1.0"
+source = { editable = "directory" }
+dependencies = [
+    { name = "mews" },
+    { name = "waitress" },
+]
+
+[package.dev-dependencies]
+dev = [
+    { name = "pytest" },
+]
+
+[package.metadata]
+requires-dist = [
+    { name = "mews", editable = "validator" },
     { name = "waitress", specifier = ">=3.0" },
 ]
 
 [package.metadata.requires-dev]
-dev = [
-    { name = "mistune", specifier = ">=3.0" },
-    { name = "pytest", specifier = ">=8.0" },
-    { name = "ruff", specifier = ">=0.15" },
-]
+dev = [{ name = "pytest", specifier = ">=8.0" }]
+
+[[package]]
+name = "mews-quickstart"
+version = "0.1.0"
+source = { editable = "quickstart" }
 
 [[package]]
 name = "mistune"