Add self-hosted Plausible analytics to all pages and post template

Oliver asked for our self-hosted Plausible snippet on oc-guy.com. The
template edit matters most: the daily sync only writes pages for new
posts, so a page-level-only change would be lost on the next generated
post. Both existing blog pages were updated directly to match the
template exactly, so the next sync produces no head diff.

The snippet is async and renders nothing: no visual change, no touch to
CSS, layout or copy.

scripts/sync_posts.py

@@ -208,6 +208,12 @@ POST_PAGE = """<!DOCTYPE html>
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
 <link href="https://fonts.googleapis.com/css2?family=Fraunces:ital,opsz,wght@0,9..144,300..700;1,9..144,300..600&family=Inter:wght@400;500;600&display=swap" rel="stylesheet">
+<!-- Privacy-friendly analytics by Plausible -->
+<script async src="https://plausible.office.odoo4projects.com/js/pa-rN8268mNMAUdwSbE2e1wZ.js"></script>
+<script>
+  window.plausible=window.plausible||function(){{(plausible.q=plausible.q||[]).push(arguments)}},plausible.init=plausible.init||function(i){{plausible.o=i||{{}}}};
+  plausible.init()
+</script>
 <link rel="stylesheet" href="../css/site.css">
 </head>
 <body>