feat(core): Change workflow deletions to soft deletes (#14894)

Adds soft‑deletion support for workflows through a new boolean column `isArchived`.

When a workflow is archived we now set `isArchived` flag to true and the workflows
stays in the database and is omitted from the default workflow listing query.

Archived workflows can be viewed in read-only mode, but they cannot be activated.

Archived workflows are still available by ID and can be invoked as sub-executions,
so existing Execute Workflow nodes continue to work. Execution engine doesn't
care about isArchived flag.

Users can restore workflows via Unarchive action at the UI.

packages/frontend/editor-ui/src/constants.ts

@@ -614,6 +614,8 @@ export const enum WORKFLOW_MENU_ACTIONS {
 	PUSH = 'push',
 	SETTINGS = 'settings',
 	DELETE = 'delete',
+	ARCHIVE = 'archive',
+	UNARCHIVE = 'unarchive',
 	SWITCH_NODE_VIEW_VERSION = 'switch-node-view-version',
 	RENAME = 'rename',
 }