feat(telemetry): track settings changes (#6504)

Summary
- Add telemetry event for settings changes when the global settings
dialog is open
- Clarify variable names in settings store (`settingParameter`,
`settingType`) for readability
- Introduce `SettingChangedMetadata` and
`TelemetryEvents.SETTING_CHANGED`
- Implement `trackSettingChanged` in Mixpanel provider
- Add focused unit test to verify telemetry triggers when settings
dialog is open vs closed

Quality
- Ran `pnpm lint:fix` and `pnpm typecheck`
- Unit tests pass locally

Notes
- Event fires only when the settings dialog is open (uses
`useDialogStore().isDialogOpen('global-settings')`)
- OSS builds are unaffected (`useTelemetry()` returns null)

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6504-feat-telemetry-track-settings-changes-clarify-names-add-unit-test-29e6d73d3650815ea919d832b310cc46)
by [Unito](https://www.unito.io)

src/platform/settings/components/SettingItem.vue

@@ -31,6 +31,8 @@ import FormItem from '@/components/common/FormItem.vue'
 import { st } from '@/i18n'
 import { useSettingStore } from '@/platform/settings/settingStore'
 import type { SettingOption, SettingParams } from '@/platform/settings/types'
+import { useTelemetry } from '@/platform/telemetry'
+import type { Settings } from '@/schemas/apiSchema'
 import { normalizeI18nKey } from '@/utils/formatUtil'
 
 const props = defineProps<{
@@ -75,7 +77,22 @@ const formItem = computed(() => {
 
 const settingStore = useSettingStore()
 const settingValue = computed(() => settingStore.get(props.setting.id))
-const updateSettingValue = async (value: any) => {
-  await settingStore.set(props.setting.id, value)
+const updateSettingValue = async <K extends keyof Settings>(
+  newValue: Settings[K]
+) => {
+  const telemetry = useTelemetry()
+  const settingId = props.setting.id
+  const previousValue = settingValue.value
+
+  await settingStore.set(settingId, newValue)
+
+  const normalizedValue = settingStore.get(settingId)
+  if (previousValue !== normalizedValue) {
+    telemetry?.trackSettingChanged({
+      setting_id: settingId,
+      previous_value: previousValue,
+      new_value: normalizedValue
+    })
+  }
 }
 </script>