Enhance SMTP configuration in docker-compose and email handler

- Updated docker-compose.yml to include optional SMTP settings with comments for clarity on configuration.
- Modified email-handler.ts to prioritize FROM_EMAIL for the sender address, falling back to SMTP_USER or ADMIN_EMAIL if not set, improving email handling flexibility.

.cursor/worktrees.json

@@ -0,0 +1,5 @@
+{
+  "setup-worktree": [
+    "npm install"
+  ]
+}