feat: implement `OnceLock`#519

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chise0713:once_lock

Commits on Apr 11, 2026

feat: implement `OnceLock`
chise0713
committed

Commits on Apr 15, 2026

fix: `OnceLock::get_or_try_init` and its mut variant
chise0713
committed

Commits on Apr 19, 2026

refactor(`Once`): replace bool flags with enum
chise0713
committed