feat(preemptive-compaction): implement automatic session compaction at token threshold

Monitor token usage after assistant responses and automatically trigger session
compaction when exceeding configured threshold (default 80%). Toast notifications
provide user feedback on compaction status.

Controlled via experimental.preemptive_compaction config option.

🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)

src/hooks/index.ts

@@ -8,6 +8,7 @@ export { createDirectoryAgentsInjectorHook } from "./directory-agents-injector";
 export { createDirectoryReadmeInjectorHook } from "./directory-readme-injector";
 export { createEmptyTaskResponseDetectorHook } from "./empty-task-response-detector";
 export { createAnthropicAutoCompactHook, type AnthropicAutoCompactOptions } from "./anthropic-auto-compact";
+export { createPreemptiveCompactionHook, type PreemptiveCompactionOptions } from "./preemptive-compaction";
 export { createThinkModeHook } from "./think-mode";
 export { createClaudeCodeHooksHook } from "./claude-code-hooks";
 export { createRulesInjectorHook } from "./rules-injector";