feat: track app mode entry and shared workflow loading (#9720)

## Summary

- Track entering app mode from template URL (`source: template_url`) and
default view dialog (`source: default_view_dialog`)
- Tag shared workflow loads with `openSource: 'shared'` instead of
defaulting to `'unknown'`
- Rename telemetry event from `app:toggle_linear_mode` to
`app:app_mode_opened`

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9720-feat-track-app-mode-entry-and-shared-workflow-loading-31f6d73d365081af8c6ae3247a50cf3f)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/components/builder/useAppSetDefaultView.ts

@@ -1,6 +1,7 @@
 import { computed } from 'vue'
 
 import { useAppMode } from '@/composables/useAppMode'
+import { useTelemetry } from '@/platform/telemetry'
 import { useWorkflowStore } from '@/platform/workflow/management/stores/workflowStore'
 import { app } from '@/scripts/app'
 import { useDialogService } from '@/services/dialogService'
@@ -54,6 +55,7 @@ export function useAppSetDefaultView() {
         appliedAsApp,
         onViewApp: () => {
           closeAppliedDialog()
+          useTelemetry()?.trackEnterLinear({ source: 'app_builder' })
           setMode('app')
         },
         onExitToWorkflow: () => {