Add the cnxvinyl.lol test site with a Gitea deploy workflow

site/ builds the internal test site: public/ served as is (landing page,
robots.txt, static sites) plus demo pages copied out of docs/ (the plant
operation page at /demos/plant-operation/). build.sh fails on dead
internal links and stamps version.txt.

.gitea/workflows/deploy-site.yml rsyncs site/dist to the buildfor.life
web server with the blog's two-directory rename swap, checks version.txt
on the server, purges Cloudflare when a token is set, and checks the
public URL. Secret names match the blog's workflow.

site/Caddyfile is the virtual host to append on s1 (noindex everywhere,
Cloudflare-only like the blog apex, www redirect). site/README.md has the
one-time setup: DNS, Caddy, web root, secrets, runner.

.gitignore

@@ -23,3 +23,6 @@ node_modules/
 
 # Playwright MCP session output
 .playwright-mcp/
+
+# Test site build output (site/build.sh)
+site/dist/