Update changelog for custom agents and /delegate command

Added support for custom agents and a new /delegate command for task delegation.

Fix formatting of changelog entry for clarity

0.0.351

0.0.350

0.0.349

0.0.348

0.0.347

Update changelog for version 0.0.346

Added entry for version 0.0.346 detailing a bug fix related to premium request usage.

0.0.345 - bugfix!

Update changelog for 0.0.344