Initial scaffold: reader-magnet course stub for thistleandmoth.org

Mirrors michaelferrara-eec-courses. course.yml is active: false and
all copy is TODO until the real reader-magnet file/cover art are
ready and the thistleandmoth-list Listmonk list exists.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

courses/reader-magnet/day-1.md

@@ -0,0 +1,5 @@
+---
+subject: "TODO: day-1 follow-up subject"
+---
+
+TODO: day-1 follow-up copy goes here.