[FEATURE] Add --quiet flag for minimal output (scripting mode)

[jwesleye]

Feature Description

Minimal output mode for use in scripts - suppress banners, status, and formatting.

Problem/Motivation

When using chat_loop in scripts, the colorful banners and status bars break parsing and look messy in logs.

Proposed Solution

echo "What is 2+2?" | chat_loop myagent --quiet
# Just outputs: 4

# Compare to normal:
# [Banner]
# [Loading messages]
# You: What is 2+2?
# Agent: 4
# [Token info]

Benefits

• Clean output for scripting
• Works with other Unix tools
• Useful in CI/CD logs
• Simpler than full --pipe mode for basic use

Priority

• Critical
• High
• Medium
• Low

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity.
It will be closed in 14 days if no further activity occurs.

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Thank you for your contributions!

[jwesleye]

Closing as not planned. The chat loop is primarily designed for interactive use with rich formatting and visual feedback. For scripting/automation use cases, users should interact directly with the AWS Strands agent rather than through the chat_loop CLI wrapper.