add db connection, refactor code, add db migration files

internal/foundry/errors.go

@@ -6,8 +6,7 @@ import (
 )
 
 var (
-	ErrorSidWrongFormat = errors.New("Session id wrong format")
-	ErrorSidNotFound    = errors.New("Session id didn't find in response header")
+	ErrorFoundryNotInit = errors.New("Foundry is not initialized")
 	ErrorAuthPassWrong  = errors.New("Authentication password is wrong")
 	ErrorNotAuth        = errors.New("Admin is not authenticated")
 	ErrorIsNotReady     = errors.New("Connection is not ready for communication")
@@ -21,7 +20,7 @@ var (
 
 type FoundryError struct {
 	Err     error
-	Type    FoundryCode
+	Type    TransportCode
 	IsFatal bool
 }