fix(cli): normalize stats model aggregation

[OnlyYu1996]

Fixes PlatformNetwork/bounty-challenge#53225.

Summary

• normalize the stats by-model aggregation key case-insensitively
• keep verbose output grouped under one canonical lower-case model ID such as gpt-4o
• apply the same normalization to default pricing lookup so GPT-4O uses the gpt-4o pricing instead of the fallback
• add regression coverage for mixed-case session files

Validation

• cargo +1.90.0 fmt --package cortex-cli --check
• git diff --check
• isolated rustc +1.90.0 --edition=2024 --test harness covering case-normalized aggregation and case-insensitive GPT-4O pricing

Targeted cargo +1.90.0 test -p cortex-cli ... is blocked locally on Windows before tests run by the existing aws-lc-sys MSVC C build failure (cl.exe exits while compiling aws-lc). The focused harness above validates the changed aggregation and pricing behavior.

[greptile-apps]

Your free trial has ended. If you'd like to continue receiving code reviews, you can add a payment method here.