feat(vscode): Wire up OpenCode chat UI in webview (2)

[markijbema]

Summary

This PR wires up the OpenCode chat UI in the VS Code extension webview, establishing the communication layer between the webview and the extension host, which in turn bridges to the CLI backend.

Key Changes

New Files

• src/shared/chat-protocol.ts - Typed message protocol for webview ↔ extension communication
• src/controllers/ChatController.ts - Extension-host controller bridging webview to CLI backend
• webview-ui/src/transport/ - Webview-side transport layer with Solid.js context
• webview-ui/src/views/ChatView.tsx - Minimal chat UI component with message timeline and prompt input
• NOTES.md - Architecture documentation

Modified Files

• esbuild.js - Added alias plugin for @/ imports
• package.json - Added dependencies (solid-js, eventsource)
• webview-ui/tsconfig.json - Added path aliases
• src/KiloProvider.ts - Updated to use ChatController
• webview-ui/src/App.tsx - Updated to render ChatView with TransportProvider

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                         VS Code Extension                        │
├─────────────────────────────────────────────────────────────────┤
│  Webview (browser)              │  Extension Host (Node.js)     │
│  ─────────────────              │  ─────────────────────────    │
│  ChatView.tsx                   │  ChatController.ts            │
│       │                         │       │                       │
│       ▼                         │       ▼                       │
│  TransportProvider ◄──postMsg──►│  KiloProvider                 │
│       │                         │       │                       │
│       ▼                         │       ▼                       │
│  chat-transport.ts              │  cli-backend-bridge.ts        │
│                                 │       │                       │
│                                 │       ▼                       │
│                                 │  HTTP/SSE to CLI backend      │
└─────────────────────────────────────────────────────────────────┘

Known Limitations

• Chat UI is minimal (basic message display and input)
• No markdown rendering yet
• No tool call visualization
• Session management is basic (single session)

Testing Instructions

1. Build the extension: pnpm compile
2. Press F5 to launch Extension Development Host
3. Open the Kilo sidebar panel
4. The chat UI should load and connect to the CLI backend
5. Type a message and press Enter to send

Next Steps

• Add markdown rendering for assistant messages
• Implement tool call visualization
• Add session list/switching
• Improve error handling and reconnection logic