Merge S7 (a1): newsletter — THE VYNDR REPORT

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

# Conflicts:
#	BUILD-STATE.md
#	CLAUDE.md

src/app.js

@@ -184,6 +184,9 @@ app.use('/api/books', bookComparisonRoutes);
 // generated from live data, degrading gracefully by data level.
 const contentRoutes = require('./routes/content');
 app.use('/api/content', contentRoutes);
+// Session S7 (a1) — THE VYNDR REPORT: public double-opt-in subscribe
+// (forwards to the self-hosted Listmonk; graceful no-op without env).
+app.use('/api/newsletter', require('./routes/newsletter'));
 // Session 18 — internal ops endpoints (admin dashboard triggers,
 // shared-key auth via `VYNDR_INTERNAL_KEY`). Never reachable from
 // the public surface; the Next.js admin route proxies through with