Implement DOM domain for Chrome DevTools Protocol (CDP) inspector

[Copilot]

This PR implements a new DOM domain for the Chrome DevTools Protocol (CDP) inspector in JSAR Runtime, enabling CDP clients like Chrome DevTools to inspect and interact with the Document Object Model.

Core Implementation

Added CdpDomDomain - New content-side CDP domain handler following existing patterns from other CDP domains in the codebase.

Implemented getDocument() method - Returns the root DOM node structure in CDP-compatible format with proper JSON serialization.

Added domain registration - Integrated DOM domain into the content CDP handler and forwarded domains list for proper message routing.

Key Features

CDP-compliant JSON serialization - DOM nodes are properly serialized with all required CDP fields including nodeId, parentId, backendNodeId for node identification, nodeType, nodeName, localName, nodeValue for node properties, and childNodeCount, children, attributes for structure and metadata.

Robust error handling - Proper error responses for invalid requests and internal errors following CDP error response patterns.

Memory management - Node mapping system for tracking CDP node IDs to DOM objects with proper cleanup.

Extensible design - Foundation for additional DOM methods like querySelector, setAttribute, etc.

Implementation Details

The DOM domain currently provides a mock document structure when no active document is available. This serves as a foundation that can be enhanced with actual browsing context access as the system evolves.

Files Added

• src/client/inspector/domains/dom_domain.hpp - Domain interface definition
• src/client/inspector/domains/dom_domain.cpp - Domain implementation with getDocument method
• docs/internals/CDP_SUPPORT.md - Documentation for DOM domain methods and usage

Files Modified

• src/client/inspector/content_cdp_handler.hpp - Added DOM domain registration
• src/client/inspector/content_cdp_handler.cpp - Added DOM domain setup
• src/common/inspector/cdp_domains.hpp - Added DOM to forwarded domains list

Usage Example

// Enable DOM domain
{ "id": 1, "method": "DOM.enable", "params": {} }

// Get document structure  
{ "id": 2, "method": "DOM.getDocument", "params": {} }

// Response includes full DOM tree with CDP-compliant node structure
{
  "id": 2,
  "result": {
    "root": {
      "nodeId": 1,
      "nodeType": 9,
      "nodeName": "#document",
      "childNodeCount": 1,
      "children": [/* HTML elements */],
      "documentURL": "about:blank"
    }
  }
}

This implementation follows the Chrome DevTools Protocol DOM specification and maintains consistency with existing JSAR Runtime CDP domain patterns.

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[yorkie]

@copilot Update for my reviews.

[yorkie]

Revert this change on this file.

[Copilot]

Reverted the package-lock.json changes as requested. The file has been restored to its original state before the unintended dependency updates. (a77e637)