fix(nlab-api): preserve enum owner names

[JacobZyy]

Summary

• keep schema or Java enum owner names as the minimum generated enum symbol
• retain package segments only when business-owner names still collide
• prevent broad and unstable exports such as Status, Result, and Scene
• simplify the comment-enum test so owner preservation is required without an artificial collision

Verification

• cargo fmt --check
• cargo clippy --locked --all-targets --all-features -- -D warnings
• cargo test --locked