[Bug] SessionStart hook systemMessage no longer displayed in TUI (v2.1.119)

Bug Description

SessionStart hook's systemMessage output is no longer displayed in the Claude Code TUI after v2.1.119 update.

Steps to Reproduce

Configure a SessionStart hook in ~/.claude/settings.json:

{
  "hooks": {
    "SessionStart": [{
      "hooks": [{
        "type": "command",
        "command": "echo '{\"systemMessage\": \"test\"}'"
      }]
    }]
  }
}

Then start a new Claude Code session.

Expected Behavior

TUI automatically shows SessionStart:startup says: ... banner at session start — without any user input required.

This is the intended use: the TUI notification allows users to see hook output (e.g., git pull results, config sync status) immediately when a session opens, without needing to type anything first.

Actual Behavior

systemMessage is injected into Claude's context (Claude can read it), but nothing is displayed in the TUI. No visible notification appears at session start.

Version Info

• Claude Code: v2.1.119
• OS: Windows 10 Pro 10.0.19045
• Previously working correctly: v2.1.117