chore(domain): yourplatform.com → breakpilot.com

Apply the platform-domain decision (2026-05-18) to every manifest,
overlay, DNS template, README, and script in this repo.

Refs: M1.1

manifests/vm-control/stalwart.toml

@@ -5,7 +5,7 @@
 name = "stalwart"
 image = "stalwartlabs/mail-server:latest"
 port = 587
-domain = "mail.yourplatform.com"
+domain = "mail.breakpilot.com"
 extra_ports = ["25:25", "465:465", "587:587", "993:993"]
 
 [service.placement]
@@ -19,4 +19,4 @@ cpu = 0.5
 path = "/opt/stalwart-mail"
 
 [service.env]
-STALWART__SERVER__HOSTNAME = "mail.yourplatform.com"
+STALWART__SERVER__HOSTNAME = "mail.breakpilot.com"