docs: update changelog for v0.6.1

docs: update changelog for v0.6.0

docs: update changelog for v0.5.4

Chief v0.5.3

docs: update changelog for v0.5.2

docs: update changelog for v0.5.1

docs: update changelog for v0.5.0

docs: add CHANGELOG.md with full release history

fix(loop): close events channel when loop finishes

The events channel was never closed after Run() returned, causing the
Manager's event forwarding goroutine to block indefinitely. This led to
the TUI becoming unresponsive after a ralph loop completed.

feat(tui): add syntax highlighting for code snippets in log view

Use Chroma library with Tokyo Night theme to highlight code from Read
tool results. Detects language from file extension and strips line
number prefixes from output before highlighting.