[refactor] Migrate manager code to DDD structure (#5662)

## Summary

Reorganized custom nodes manager functionality from scattered technical
layers into a cohesive domain-focused module following [domain-driven
design](https://en.wikipedia.org/wiki/Domain-driven_design) principles.

## Changes

- **What**: Migrated all manager code from technical layers
(`src/components/`, `src/stores/`, etc.) to unified domain structure at
`src/workbench/extensions/manager/`
- **Breaking**: Import paths changed for all manager-related modules
(40+ files updated)

## Review Focus

Verify all import path updates are correct and no circular dependencies
introduced. Check that [Vue 3 composition
API](https://vuejs.org/guide/reusability/composables.html) patterns
remain consistent across relocated composables.


┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5662-refactor-Migrate-manager-code-to-DDD-structure-2736d73d3650812c87faf6ed0fffb196)
by [Unito](https://www.unito.io)

src/components/dialog/content/manager/ManagerHeader.test.ts

@@ -1,82 +0,0 @@
-import { mount } from '@vue/test-utils'
-import { createPinia } from 'pinia'
-import PrimeVue from 'primevue/config'
-import Tag from 'primevue/tag'
-import Tooltip from 'primevue/tooltip'
-import { describe, expect, it } from 'vitest'
-import { createI18n } from 'vue-i18n'
-
-import enMessages from '@/locales/en/main.json' with { type: 'json' }
-
-import ManagerHeader from './ManagerHeader.vue'
-
-const i18n = createI18n({
-  legacy: false,
-  locale: 'en',
-  messages: {
-    en: enMessages
-  }
-})
-
-describe('ManagerHeader', () => {
-  const createWrapper = () => {
-    return mount(ManagerHeader, {
-      global: {
-        plugins: [createPinia(), PrimeVue, i18n],
-        directives: {
-          tooltip: Tooltip
-        },
-        components: {
-          Tag
-        }
-      }
-    })
-  }
-
-  it('renders the component title', () => {
-    const wrapper = createWrapper()
-
-    expect(wrapper.find('h2').text()).toBe(
-      enMessages.manager.discoverCommunityContent
-    )
-  })
-
-  it('displays the legacy manager UI tag', () => {
-    const wrapper = createWrapper()
-
-    const tag = wrapper.find('[data-pc-name="tag"]')
-    expect(tag.exists()).toBe(true)
-    expect(tag.text()).toContain(enMessages.manager.legacyManagerUI)
-  })
-
-  it('applies info severity to the tag', () => {
-    const wrapper = createWrapper()
-
-    const tag = wrapper.find('[data-pc-name="tag"]')
-    expect(tag.classes()).toContain('p-tag-info')
-  })
-
-  it('displays info icon in the tag', () => {
-    const wrapper = createWrapper()
-
-    const icon = wrapper.find('.pi-info-circle')
-    expect(icon.exists()).toBe(true)
-  })
-
-  it('has cursor-help class on the tag', () => {
-    const wrapper = createWrapper()
-
-    const tag = wrapper.find('[data-pc-name="tag"]')
-    expect(tag.classes()).toContain('cursor-help')
-  })
-
-  it('has proper structure with flex container', () => {
-    const wrapper = createWrapper()
-
-    const flexContainer = wrapper.find('.flex.justify-end.ml-auto.pr-4')
-    expect(flexContainer.exists()).toBe(true)
-
-    const tag = flexContainer.find('[data-pc-name="tag"]')
-    expect(tag.exists()).toBe(true)
-  })
-})