feat: App mode saving rework (#9338)

## Summary

Change app mode changes to be written directly to the workflow on change
instead of requiring explicit save via builder.
Temporary: Adds `.app.json` file extension to app files for
identification since we don't currently have a way to identify them with
metadata
Removes app builder save dialog and replaces it with default mode
selection

## Changes

- **What**: 
- ensure all save locations handle app mode
- remove dirtyLinearData and flushing

- **Breaking**: 
- if people are relying on workflow names and are converting to/from app
mode in the same workflow, they will gain/lose the `.app` part of the
extension

## Screenshots (if applicable)

<img width="689" height="84" alt="image"
src="https://github.com/user-attachments/assets/335596ee-dce9-4e3a-a7b5-f0715c294e41"
/>

<img width="421" height="324" alt="image"
src="https://github.com/user-attachments/assets/ad3cd33c-e9f0-4c30-8874-d4507892fc6b"
/>

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9338-feat-App-mode-saving-rework-3176d73d3650813f9ae1f6c5a234da8c)
by [Unito](https://www.unito.io)

src/components/builder/useAppSetDefaultView.test.ts

@@ -0,0 +1,146 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const mockDialogService = vi.hoisted(() => ({
+  showLayoutDialog: vi.fn()
+}))
+
+const mockDialogStore = vi.hoisted(() => ({
+  closeDialog: vi.fn(),
+  isDialogOpen: vi.fn<(key: string) => boolean>().mockReturnValue(false)
+}))
+
+const mockWorkflowStore = vi.hoisted(() => ({
+  activeWorkflow: null as { initialMode?: string | null } | null
+}))
+
+const mockApp = vi.hoisted(() => ({
+  rootGraph: { extra: {} as Record<string, unknown> }
+}))
+
+vi.mock('@/services/dialogService', () => ({
+  useDialogService: () => mockDialogService
+}))
+
+vi.mock('@/stores/dialogStore', () => ({
+  useDialogStore: () => mockDialogStore
+}))
+
+vi.mock('@/platform/workflow/management/stores/workflowStore', () => ({
+  useWorkflowStore: () => mockWorkflowStore
+}))
+
+vi.mock('@/scripts/app', () => ({
+  app: mockApp
+}))
+
+vi.mock('./DefaultViewDialogContent.vue', () => ({
+  default: { name: 'MockDefaultViewDialogContent' }
+}))
+
+import { useAppSetDefaultView } from './useAppSetDefaultView'
+
+describe('useAppSetDefaultView', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    mockWorkflowStore.activeWorkflow = null
+    mockApp.rootGraph.extra = {}
+  })
+
+  describe('settingView', () => {
+    it('reflects dialogStore.isDialogOpen', () => {
+      mockDialogStore.isDialogOpen.mockReturnValue(true)
+      const { settingView } = useAppSetDefaultView()
+      expect(settingView.value).toBe(true)
+    })
+  })
+
+  describe('showDialog', () => {
+    it('opens dialog via dialogService', () => {
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      expect(mockDialogService.showLayoutDialog).toHaveBeenCalledOnce()
+    })
+
+    it('passes initialOpenAsApp true when initialMode is not graph', () => {
+      mockWorkflowStore.activeWorkflow = { initialMode: 'app' }
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      expect(call.props.initialOpenAsApp).toBe(true)
+    })
+
+    it('passes initialOpenAsApp false when initialMode is graph', () => {
+      mockWorkflowStore.activeWorkflow = { initialMode: 'graph' }
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      expect(call.props.initialOpenAsApp).toBe(false)
+    })
+
+    it('passes initialOpenAsApp true when no active workflow', () => {
+      mockWorkflowStore.activeWorkflow = null
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      expect(call.props.initialOpenAsApp).toBe(true)
+    })
+  })
+
+  describe('handleApply', () => {
+    it('sets initialMode to app when openAsApp is true', () => {
+      const workflow = { initialMode: null as string | null }
+      mockWorkflowStore.activeWorkflow = workflow
+
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      call.props.onApply(true)
+
+      expect(workflow.initialMode).toBe('app')
+    })
+
+    it('sets initialMode to graph when openAsApp is false', () => {
+      const workflow = { initialMode: null as string | null }
+      mockWorkflowStore.activeWorkflow = workflow
+
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      call.props.onApply(false)
+
+      expect(workflow.initialMode).toBe('graph')
+    })
+
+    it('sets linearMode on rootGraph.extra', () => {
+      mockWorkflowStore.activeWorkflow = { initialMode: null }
+
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      call.props.onApply(true)
+
+      expect(mockApp.rootGraph.extra.linearMode).toBe(true)
+    })
+
+    it('closes dialog after applying', () => {
+      mockWorkflowStore.activeWorkflow = { initialMode: null }
+
+      const { showDialog } = useAppSetDefaultView()
+      showDialog()
+
+      const call = mockDialogService.showLayoutDialog.mock.calls[0][0]
+      call.props.onApply(true)
+
+      expect(mockDialogStore.closeDialog).toHaveBeenCalledWith({
+        key: 'builder-default-view'
+      })
+    })
+  })
+})