[FEATURE] Show token usage and cost after each response

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Display token count and estimated cost at the bottom of each response
To monitor API usage and costs in real-time without needing to check the dashboard separately

Proposed Solution

Example format at response end:
Tokens used: 5,234 | Est. cost: $0.15 | Total session: 45,234 tokens

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_