fix(auth): ignore whitespace-only environment auth tokens

[694410194]

Summary

• treat whitespace-only CORTEX_AUTH_TOKEN and CORTEX_API_KEY values as missing in cortex whoami
• keep cortex login status and shared auth availability checks consistent with the same normalization
• add focused auth-token unit coverage for whitespace-only values

Related to PlatformNetwork/bounty-challenge#47006.

Verification

• git diff --check
• static review of the updated auth checks

Note: I could not run cargo test / cargo check in this environment because the Rust toolchain is not installed in PATH.

[greptile-apps]

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