CacheBell 0.3.0

CacheBell now works with OpenCode 2 and OpenCode 1 from the same package.

• Version 2 drives the bell through the model.request session hook and the subscribed event stream; version 1 keeps using chat.headers. The logic that decides when a window opens, when cache reads or writes confirm it, and when the bell is due is shared.
• Titles, summaries and compactions no longer arm a window — nobody is waiting on those.
• Version 2 runs one plugin instance per location against one shared event stream, so a session now rings only in the instance whose directory owns it.
• 41 passing tests.

Upgrade the OpenCode plugin entry to opencode-cachebell@0.3.0 and restart.