Add email support with notmuch, mbsync, and msmtp

Set up complete email workflow in Emacs using:
- notmuch for email indexing and UI
- mbsync for IMAP synchronization from proton.johnogle.info
- msmtp for SMTP sending via port 25 with PLAIN auth
- systemd timer for automatic sync every 5 minutes

Configuration includes:
- New email role at home/roles/email with all mail tools
- Doom Emacs notmuch module enabled with saved searches
- Secure credential retrieval via rbw from Bitwarden
- Fixed systemd service PATH to access rbw-agent
- TLS/STARTTLS for secure connections

Email role enabled on nix-book (laptop-compact profile).

home/home-laptop-compact.nix

@@ -14,6 +14,7 @@
     desktop.enable = true;
     development.enable = true;
     communication.enable = true;
+    email.enable = true;
     kdeconnect.enable = true;
     media.enable = true;
     sync.enable = true;