chore: release v1.20.1

[ErickXavier]

Summary

• Version bump to 1.20.1 across package.json, package-lock.json, and src/index.js
• CHANGELOG.md updated with all changes since v1.20.0

Highlights

• Fixed: get-insert append/prepend duplicate rendering, IntersectionObserver root on pagination observers, i18n post-init guard, prepend scroll compensation under animate-leave
• Hardened: e2e suite (deterministic waits, Elements skip-guard), unit coverage for template+animate-stagger
• Docs: loops Common Mistakes callout, locale-list dedupe, ADR-002, Google Analytics, observer-root semantics
• Chore: dependency bumps (jest-dom 7.0.0, jsdom 30.0.0, eslint 10.8.0, playwright 1.62.0, commitlint 21.2.1, setup-node 7)

Test plan

• node build.js succeeds
• grep -c "1.20.1" dist/iife/no.js returns 2
• gzip size: 44,184 bytes (within 44,500 bound)
• npm test — 2232 tests pass (42 suites)
• dist/ artifacts committed