docs: fix changelog release notes

[f0rr0]

Summary

• correct the 0.1.0 changelog date to the actual September 27, 2025 release date
• align the 0.3.0 changelog section with the GitHub release-note format

Validation

• scripts/validate.sh pre-commit
• pre-push hook via git push: git diff --check, cargo clippy --all-targets --locked -- -D warnings, cargo test --all-targets --locked -- --nocapture