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)

tests-ui/tests/platform/settings/components/SettingItem.test.ts

@@ -0,0 +1,107 @@
+import { flushPromises, shallowMount } from '@vue/test-utils'
+import { describe, expect, it, vi, beforeEach } from 'vitest'
+
+import SettingItem from '@/platform/settings/components/SettingItem.vue'
+import type { SettingParams } from '@/platform/settings/types'
+import { i18n } from '@/i18n'
+
+/**
+ * Verifies that SettingItem emits telemetry when its value changes
+ * and suppresses telemetry when the value remains the same.
+ */
+const trackSettingChanged = vi.fn()
+vi.mock('@/platform/telemetry', () => ({
+  useTelemetry: vi.fn(() => ({
+    trackSettingChanged
+  }))
+}))
+
+const mockGet = vi.fn()
+const mockSet = vi.fn()
+vi.mock('@/platform/settings/settingStore', () => ({
+  useSettingStore: () => ({
+    get: mockGet,
+    set: mockSet
+  })
+}))
+
+/**
+ * Minimal stub for FormItem that allows emitting `update:form-value`.
+ */
+const FormItemUpdateStub = {
+  template: '<div />',
+  emits: ['update:form-value'],
+  props: ['id', 'item', 'formValue']
+}
+
+describe('SettingItem (telemetry UI tracking)', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  const mountComponent = (setting: SettingParams) => {
+    return shallowMount(SettingItem, {
+      global: {
+        plugins: [i18n],
+        stubs: {
+          FormItem: FormItemUpdateStub,
+          Tag: true
+        }
+      },
+      props: {
+        setting
+      }
+    })
+  }
+
+  it('tracks telemetry when value changes via UI (uses normalized value)', async () => {
+    const settingParams: SettingParams = {
+      id: 'main.sub.setting.name',
+      name: 'Telemetry Visible',
+      type: 'text',
+      defaultValue: 'default'
+    }
+
+    mockGet.mockReturnValueOnce('default').mockReturnValueOnce('normalized')
+    mockSet.mockResolvedValue(undefined)
+
+    const wrapper = mountComponent(settingParams)
+
+    const newValue = 'newvalue'
+    const formItem = wrapper.findComponent(FormItemUpdateStub)
+    formItem.vm.$emit('update:form-value', newValue)
+
+    await flushPromises()
+
+    expect(trackSettingChanged).toHaveBeenCalledTimes(1)
+    expect(trackSettingChanged).toHaveBeenCalledWith(
+      expect.objectContaining({
+        setting_id: 'main.sub.setting.name',
+        previous_value: 'default',
+        new_value: 'normalized'
+      })
+    )
+  })
+
+  it('does not track telemetry when normalized value does not change', async () => {
+    const settingParams: SettingParams = {
+      id: 'main.sub.setting.name',
+      name: 'Telemetry Visible',
+      type: 'text',
+      defaultValue: 'same'
+    }
+
+    mockGet.mockReturnValueOnce('same').mockReturnValueOnce('same')
+    mockSet.mockResolvedValue(undefined)
+
+    const wrapper = mountComponent(settingParams)
+
+    const unchangedValue = 'same'
+    const formItem = wrapper.findComponent(FormItemUpdateStub)
+    formItem.vm.$emit('update:form-value', unchangedValue)
+
+    await flushPromises()
+
+    expect(trackSettingChanged).not.toHaveBeenCalled()
+  })
+})