[BUG] PostToolUse hook blocks Edit diff rendering in CLI

Version: 2.1.114
OS: Windows 11, CLI

When a long-running PostToolUse hook fires after Edit, the CLI withholds the diff until the hook exits. Diff + hook stdout appear together after the full duration — with a 30–60s hook the agent appears completely frozen.

VS Code extension handles this correctly: diff renders immediately, hook output appears after. CLI should match.

Repro:

1. Configure a PostToolUse hook on Edit that takes 30+ seconds
2. Claude edits a file in CLI
3. Diff is not shown until hook completes

Related: #47692