fix: clarify active profile auth display

[Ramon Nogueira (ramon-langchain)]

Summary

• stop marking a profile active when flag/env API-key auth takes precedence
• print the env API-key precedence note below profile list and profile show tables in pretty mode
• centralize LANGSMITH_API_KEY lookup in config for the command resolver paths

Test Plan

• go test ./internal/config ./internal/cmd ./internal/cmdutil -run 'TestProfile|TestAuth|TestGetAPIKey|TestResolve'
• deslop internal/cmd/profile.go internal/cmd/profile_test.go internal/cmd/root.go internal/cmd/auth.go internal/cmdutil/resolve.go internal/config/config.go