chore: add Makefile with preview target

Adds a simple 'make preview' command that serves the website directory with Python's built-in HTTP server for local development.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: vinta

Makefile

@@ -0,0 +1,4 @@
+.PHONY: preview
+
+preview:
+	cd website && python3 -m http.server 8000