audit record --from-hook silently drops input from kiro-cli postToolUse hooks

Description

swamp audit record --from-hook --tool kiro exits 0 but does not persist any audit data when receiving postToolUse hook events from kiro-cli.

Steps to Reproduce

1. Configure a swamp agent with a postToolUse hook:

{
  "hooks": {
    "postToolUse": [
      {
        "command": "swamp audit record --from-hook --tool kiro"
      }
    ]
  }
}

1. Run swamp repo init --force to enable audit
2. Execute any tool in kiro-cli (e.g. shell command)
3. Check audit: swamp audit shows 'No audit data found'
4. Manually pipe hook JSON to the command:

echo '{"hook_event_name":"postToolUse","cwd":"/path","tool_name":"shell","tool_input":{"command":"echo test"},"tool_response":{"success":true}}' | swamp audit record --from-hook --tool kiro

Exit code 0, but swamp audit still shows no data.

Verification

A second hook logging to a file confirms the hook IS firing and STDIN contains valid JSON with full tool_input and tool_response. The issue is in swamp audit record not processing/persisting the input.

{"hook_event_name":"postToolUse","cwd":"/Users/dmc/projects/ai-infra","session_id":"...","tool_name":"shell","tool_input":{"command":"echo test"},"tool_response":{"items":[{"Json":{"exit_status":"exit status: 0","stdout":"test","stderr":""}}]}}

Environment

• swamp: 20260418.005854.0-sha.c17d3e4c
• kiro-cli: latest (hooks pass data via STDIN, not USER_PROMPT env var)
• macOS arm64