feat: Add WebEdit Agent for web page browsing and DOM selection

[phodal]

Summary

Add a new WebEdit agent type that allows users to:

• Browse web pages in an embedded WebView
• Enter selection mode to select DOM elements
• View the DOM tree structure in a sidebar
• Ask questions about the page content or selected elements

Features

Core Components

• WebEditBridge: Abstraction layer for bidirectional WebView-Kotlin communication
• DOMElement model: Data classes representing DOM structure with bounding boxes
• WebEditBridgeScript: JavaScript injection for DOM selection functionality

UI Components

• WebEditPage: Main page with URL bar, WebView area, DOM sidebar, and chat input
• WebEditToolbar: Navigation controls and mode toggles
• DOMTreeSidebar: Interactive DOM tree view
• WebEditChatInput: Q&A input for LLM integration

Platform Support

• JVM and WASM implementations of WebEditBridge
• Uses expect/actual pattern for platform-specific code

Related

This feature adds the WEB_EDIT agent type to the existing agent framework.

TODOs

• Create platform-specific WebView implementation for JVM
• Integrate JavaScript bridge script injection on page load
• Connect LLM service for page/element Q&A functionality
• Add element extraction and code generation features