v0.6.0-rc79

Improve XML parsing security and enhance message previews (#154)

This commit addresses two key improvements:

## 1. XML Parsing Security Enhancement
- Replace regex-based XML parsing with safer string-based approach
- Only search for known tool names from predefined DEFAULT_VALID_TOOLS list
- Only parse recognized parameter names, ignoring unknown parameters
- Eliminates security risk of parsing instructional/example XML as executable commands
- Maintains backward compatibility - all existing tests pass

## 2. Enhanced Message Preview Format
- Add createMessagePreview() utility function showing start+end of messages
- Upgrade from 200 chars to 400+ chars total preview (200 start + 200 end)
- Update ProbeAgent.js: user message and assistant response previews
- Update delegate.js: stdout and stderr chunk previews
- Update schemaUtils.js: JSON validation response previews
- Better debugging visibility for tool calls, completions, and response endings

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>