Fix drag-and-drop into dropdown menu items

[Copilot]

Dragging template menu items into expanded dropdown bodies placed items outside the dropdown instead of inside. This broke after migrating from dragular to Angular CDK drag-drop.

Root Cause

Dropdown bodies lacked unique IDs and weren't included in the template menu's cdkDropListConnectedTo array, preventing CDK from routing drops correctly.

Changes

navigation-menu-page.component.ts

• Added getDropdownId(index) to generate unique IDs (dropdown-0, dropdown-1, ...)
• Added connectedDropdownIds getter to dynamically build array of all dropdown IDs for connection binding

navigation-menu-page.component.html

• Assigned unique [id] to each dropdown body via getDropdownId(firstLevelIndex)
• Updated template menu's cdkDropListConnectedTo to ['actualMenuList'].concat(connectedDropdownIds)

// Component
get connectedDropdownIds(): string[] {
  return this.navigationMenuModel.actualMenu
    .map((item, index) => item.type === NavigationMenuItemTypeEnum.Dropdown ? this.getDropdownId(index) : null)
    .filter(id => id !== null) as string[];
}

<!-- Template menu now connects to all dropdowns -->
<div cdkDropList [cdkDropListConnectedTo]="['actualMenuList'].concat(connectedDropdownIds)" id="mainMenu">

<!-- Each dropdown gets unique ID -->
<div cdkDropList [id]="getDropdownId(firstLevelIndex)" [cdkDropListConnectedTo]="['mainMenu']">

This establishes bidirectional connections allowing template items to drop into any dropdown body.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>dragging a menuitem into dropdown does not work</issue_title>
<issue_description>When dragging a menuitme into an expanded dropdown places the menuitem outside the dropdown instead of inside of it. This was working before the refactor from dragular to dnd</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes dragging a menuitem into dropdown does not work #7274

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