Update AGENTS.md. Start fixing old weird errors

.env.example

@@ -17,8 +17,10 @@ NEXT_PUBLIC_SENTRY_PROJECT_NAME=example
 CONVEX_SELF_HOSTED_URL=https://api.convex.example.com # convex-backend:3210
 CONVEX_SELF_HOSTED_ADMIN_KEY= # Generate after hosted on docker
 # Convex Auth
-CONVEX_SITE_URL=https://convex.example.com # convex-backend:3211
+CONVEX_SITE_URL=http://localhost:3000 # Always localhost:3000 for local dev; update in Convex Dashboard for production
 USESEND_API_KEY=
+USESEND_URL=https://usesend.example.com
+USESEND_FROM_EMAIL=My App <[email protected]>
 AUTH_AUTHENTIK_ID=
 AUTH_AUTHENTIK_SECRET=
 AUTH_AUTHENTIK_ISSUER=