chore(cmd): rename migrate command to pulse-migrate

Author: pixel365

README.md

@@ -32,7 +32,7 @@ What exists today:
 - gRPC health checks via `grpc.health.v1.Health/Check`
 - PostgreSQL-backed raw check execution storage
 - persisted current check state
-- migration CLI via `cmd/migrate`
+- migration CLI via `cmd/pulse-migrate`
 
 What does not exist yet in a finished form: