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/platform/workflow/sharing/components/ShareUrlCopyField.vue

@@ -26,17 +26,24 @@ import { refAutoReset } from '@vueuse/core'
 
 import Button from '@/components/ui/button/Button.vue'
 import Input from '@/components/ui/input/Input.vue'
+import { useAppMode } from '@/composables/useAppMode'
 import { useCopyToClipboard } from '@/composables/useCopyToClipboard'
+import { useTelemetry } from '@/platform/telemetry'
 
 const { url } = defineProps<{
   url: string
 }>()
 
 const { copyToClipboard } = useCopyToClipboard()
+const { isAppMode } = useAppMode()
 const copied = refAutoReset(false, 2000)
 
 async function handleCopy() {
   await copyToClipboard(url)
   copied.value = true
+  useTelemetry()?.trackShareFlow({
+    step: 'link_copied',
+    source: isAppMode.value ? 'app_mode' : 'graph_mode'
+  })
 }
 </script>