Rebuild mdcms as proper CLI tool (v0.3)

- Replace interactive TUI with click-based subcommands:
  register, delete, view, build
- build accepts NAME (registry), --path, or CWD for GitHub Actions use
- Switch to PyYAML for frontmatter and nav.yml parsing
- Add pyproject.toml with click + PyYAML deps and mdcms entry point
- Add v0.3 version marker to app/config.yml and app/index.html
- Registry moves to ~/.config/mdcms/sites.json (XDG-compliant)
- Project root is now the directory containing index.html (no website/ subdir)
- register auto-downloads template from GitHub if no site found

https://claude.ai/code/session_01MqEqGhP1guGx5VuFsLaws2

app/config.yml

@@ -1,4 +1,5 @@
-# MD-CMS v0.2 — Site configuration
+# mdcms v0.3 | DO NOT REMOVE THIS COMMENT
+# MD-CMS v0.3 — Site configuration
 #
 # Only `sitename` and `navigation` are required. Uncomment and edit the rest
 # as needed. See https://kbenestad.codeberg.page/md-cms for the full reference.

app/index.html

@@ -1,5 +1,6 @@
+<!-- mdcms v0.3 | DO NOT REMOVE THIS COMMENT -->
 <!--
-  MD-CMS v0.2 — Renderer
+  MD-CMS v0.3 — Renderer
 
   Copyright 2026 Kristian Benestad | kbenestad.codeberg.page
 

pyproject.toml

@@ -0,0 +1,26 @@
+[build-system]
+requires = ["setuptools>=68", "wheel"]
+build-backend = "setuptools.backends.legacy:build"
+
+[project]
+name = "mdcms"
+version = "0.3.0"
+description = "MD-CMS — Markdown-based CMS companion CLI"
+readme = "README.md"
+license = { text = "Apache-2.0" }
+authors = [{ name = "Kristian Benestad" }]
+requires-python = ">=3.9"
+dependencies = [
+    "click>=8.0",
+    "PyYAML>=6.0",
+]
+
+[project.scripts]
+mdcms = "mdcms:main"
+
+[project.urls]
+Homepage = "https://github.com/kbenestad/mdcms"
+Documentation = "https://docs.benestad.net"
+
+[tool.setuptools]
+py-modules = ["mdcms"]