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.

cypress/pages/workflows.ts

@@ -36,6 +36,10 @@ export class WorkflowsPage extends BasePage {
 		workflowCardActions: (workflowName: string) =>
 			this.getters.workflowCard(workflowName).findChildByTestId('workflow-card-actions'),
 		workflowActionItem: (action: string) => cy.getByTestId(`action-${action}`).filter(':visible'),
+		workflowArchiveButton: () =>
+			cy.getByTestId('action-toggle-dropdown').filter(':visible').contains('Archive'),
+		workflowUnarchiveButton: () =>
+			cy.getByTestId('action-toggle-dropdown').filter(':visible').contains('Unarchive'),
 		workflowDeleteButton: () =>
 			cy.getByTestId('action-toggle-dropdown').filter(':visible').contains('Delete'),
 		workflowMoveButton: () =>
@@ -47,6 +51,7 @@ export class WorkflowsPage extends BasePage {
 		workflowStatusItem: (status: string) => cy.getByTestId('status').contains(status),
 		workflowOwnershipDropdown: () => cy.getByTestId('user-select-trigger'),
 		workflowOwner: (email: string) => cy.getByTestId('user-email').contains(email),
+		workflowArchivedCheckbox: () => cy.getByTestId('show-archived-checkbox'),
 		workflowResetFilters: () => cy.getByTestId('workflows-filter-reset'),
 		workflowSortDropdown: () => cy.getByTestId('resources-list-sort'),
 		workflowSortItem: (sort: string) =>