Apply mechanical lint fixes for golangci-lint v2.12.2 rollout

Auto-remediate style-only findings (wsl_v5, nlreturn, noinlineerr,
modernize, intrange, perfsprint, usetesting, unconvert, errorlint,
gocritic, testifylint) and rename printf-style helpers to f-suffixed
names (goprintffuncname): ui.Writer message methods, cli.ReportErrorf,
database.Fatalf, vaultik stdoutf.

internal/snapshot/remotekey.go

@@ -36,5 +36,6 @@ const remoteKeyPrefix = "vaultik|"
 func RemoteSnapshotKey(snapshotID string) string {
 	first := sha256.Sum256([]byte(remoteKeyPrefix + snapshotID))
 	second := sha256.Sum256(first[:])
+
 	return hex.EncodeToString(second[:])
 }