feat(cli): Add --quiet /-q flag to goose run

[chaitanyarahalkar]

Add --quiet /-q flag to goose run

Motivation

When running Goose in non-interactive or script environments, the CLI currently prints a banner before every response:

starting session | provider: openai model: gpt-4o
    logging to /Users/.../sessions/20250615_191939.jsonl
    working directory: /tmp/...

For pipelines that need just the model’s text, this extra output is unwanted noise.
The new --quiet flag solves this by suppressing all non-response lines.

What’s in this PR

1. CLI

   • Adds -q, --quiet to the Run sub-command.
   • Flag is parsed by clap and passed through the command handler.

2. Session builder

   • Introduces quiet: bool in SessionBuilderConfig (default false).
   • display_session_info() is skipped when quiet == true.

3. Call-sites & tests

   • All SessionBuilderConfig { … } instantiations updated to include quiet.
   • Unit tests updated accordingly.
   • Bench command helper updated (quiet = false).

Example

Mode	Example	Output
Normal	goose run -t "hi"	Banner + model response
Quiet	goose run -t "hi" --quiet goose run -t "hi" -q	Only the model response

Implementation notes

• Only the “start-session” banner (provider/model, log path, working dir) is suppressed.
• All subsequent agent responses and streamed content remain unchanged.
• No impact on interactive sessions or other sub-commands.

[zanesq]

@chaitanyarahalkar do you mind adding this to the docs also?