Add IDE Integration (`/ide` — connect to VS Code workspace)

[PureWeen]

Summary

The CLI's /ide command connects a session to an IDE workspace (VS Code) for diagnostics and file diffs. PolyPilot already launches VS Code from session context menus but doesn't use the bidirectional IDE connection.

CLI Behavior

• /ide — establish connection to IDE workspace
• Enables file diff viewing, diagnostic integration, and workspace awareness

Proposed Implementation

1. IDE connection status indicator in session header
2. "Connect to IDE" button — establish bidirectional connection
3. Diagnostic sync — show IDE diagnostics (errors, warnings) in PolyPilot
4. File diff integration — open modified files in VS Code diff view

Priority: 🟢 LOW