chore: Release v0.1.20

[shenald-dev]

• Adversarial QA completed: Verified preceding optimization prevents MarkupError exceptions when user-provided strings contain unescaped tag-like bracket characters.
• Ensured tests run successfully and dead code elimination checked out.
• Synchronized documentation in CHANGELOG.md and .jules/warden.md to reflect crash fix.
• Cut and tagged release v0.1.20.

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PR created automatically by Jules for task 6342032019642713529 started by @shenald-dev

[google-labs-jules]

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[shenald-dev]

Looks good, merging this in. CI is green and everything checks out 👍

Release v0.1.20 with documentation updates and version bump.

[google-labs-jules]

Looks good, merging this in. CI is green and everything checks out 👍

Release v0.1.20 with documentation updates and version bump.

Acknowledged.