AI Changelog Aggregator

This addresses a number of important issues reported in 0.2.0:

Fixes an issue where non-ASCII characters were crashing the CLI: https://github.com/openai/codex/issues/1450 (huge thanks to @ryozi-tn for the fix in https://github.com/openai/codex/pull/1467)
Adds support for a --sandbox flag and makes some breaking changes to config.toml around this option. See https://github.com/openai/codex/pull/1476 for details.
Makes it possible to configure custom HTTP headers when making requests to model providers: https://github.com/openai/codex/pull/1473.