fix(hooks): restore grep truncation by removing unused grep-output-truncator (#120)

The grep-output-truncator hook was never registered in index.ts, so grep
output was not being truncated since commit 03a4501 which removed grep/Grep
from tool-output-truncator's TRUNCATABLE_TOOLS list.

- Remove unused grep-output-truncator.ts
- Add "grep" and "Grep" back to tool-output-truncator's TRUNCATABLE_TOOLS

Co-authored-by: Claude <noreply@anthropic.com>

src/hooks/index.ts

@@ -3,7 +3,6 @@ export { createContextWindowMonitorHook } from "./context-window-monitor";
 export { createSessionNotification } from "./session-notification";
 export { createSessionRecoveryHook, type SessionRecoveryHook, type SessionRecoveryOptions } from "./session-recovery";
 export { createCommentCheckerHooks } from "./comment-checker";
-export { createGrepOutputTruncatorHook } from "./grep-output-truncator";
 export { createToolOutputTruncatorHook } from "./tool-output-truncator";
 export { createDirectoryAgentsInjectorHook } from "./directory-agents-injector";
 export { createDirectoryReadmeInjectorHook } from "./directory-readme-injector";