ci: add golangci-lint config and fix formatting

- Add .golangci.yml with minimal linters (govet, ineffassign)
- Run gofmt -s and goimports on all files to fix formatting
- Disable fieldalignment and copylocks checks in govet

internal/wal/encryption.go

@@ -11,6 +11,7 @@ import (
 	"path/filepath"
 
 	"dbbackup/internal/logger"
+
 	"golang.org/x/crypto/pbkdf2"
 )