[Feature Request] Support custom pre-compact, compact, and post-compact commands to run instead of default after context window is 95% full

I would personally love the option to define my own replacement for auto-compaction as a series of commands.

This could be generally automated as 3 customize-able commands with defaults:

• Pre-compact (default: none)
• Compact (default: /compact)
• Post-compact (default: none)

Bonus: set the percentage remaining in context window at which it gets triggered.

I have had a lot of problems with the results of compacting. Quality of progress drops, and /compact takes a lot of time while burning a lot of tokens. My projects require a carefully-loaded github-issue-specific context to achieve good results with CC, so I just need to rebuild my context manually whenever I see an upcoming auto-compact event.