feat(backup): take Tinyforge DB snapshot before every deploy

Adds an opt-in "auto_backup_before_deploy" setting that triggers a
"pre-deploy" backup at the start of every project deploy via the deploy
pipeline (covers both the async HTTP path and the sync poller/webhook
path). Failures are logged to the deploy log but do not abort — missing
a backup is preferable to refusing to ship a fix.

- store: settings.auto_backup_before_deploy column + scan/update wiring
- backup: accept "pre-deploy" as a valid backup_type
- deployer: small PreDeployBackuper interface, hooked into runDeploy
  right after settings load and before any state-mutating work
- api: settings request/response surface the new flag
- web: ToggleSwitch on the backup settings page; "Pre-deploy" badge
  variant in the backup list (badge-warning so it stands out)
- i18n: en/ru strings for the toggle, help text, and badge label

cmd/server/main.go

@@ -227,6 +227,7 @@ func main() {
 		slog.Error("create backup engine", "error", err)
 		os.Exit(1)
 	}
+	dep.SetPreDeployBackuper(backupEngine)
 
 	// Clean orphaned backup files and prune on startup.
 	if cleaned, err := backupEngine.CleanOrphans(); err != nil {