Status line should re-render after /clear

Problem

After running /clear, the status line disappears and doesn't re-render until the next Claude response. This means the user loses context about their current state (git branch, model, context usage) right when they might need it most — at the start of a fresh conversation.

Expected behavior

/clear should re-evaluate and re-render the status line, just like it does at session start. The status line command receives workspace/model/context JSON via stdin — after /clear, the system should pass the refreshed context and invoke the command again.

Why it matters

The status line is often configured to show the current git branch, working directory, and model. After /clear, the user starts a new conversation but has no visual indicator of which branch they're on — exactly the moment they'd want to confirm their context before starting new work.

Reproduction

1. Configure a status line in settings.json:

``json
"statusLine": {
"type": "command",
"command": "bash ~/.claude/statusline-command.sh"
}
``

1. Start Claude Code — status line renders correctly
2. Run /clear
3. Status line disappears until the next Claude response

Suggested fix

Treat /clear as a session-start event that triggers a status line refresh with the current workspace context.