test action fixes and other test fixes for feat: add support for parsing local sitemap files

[tylertech-lee-hazlett]

• GitHub Actions were failing to build because bad import syntax on core modules
• Existing tests were broken because emerald.com doesn't have a sitemap.xml any more
• Coverage tests were running successfully because an improper mock value set on Priority
• Local file tests were failing because xml was not copied to lib

---

Note

Ensures local-file parsing works end-to-end and CI passes.

• Build: Update compile to cp src/tests/*.xml lib/tests/; switch to ESM namespace imports for fs/zlib in src/assets/sitemapper.js and tests; minor example formatting.
• Tests: Replace emerald.com with google.com; adjust expectations to numeric priority; add/strengthen local file tests (fields, lastmod filtering, exclusions, gzipped files); fix imports; minor cleanup.
• Examples: Add src/examples/local-file.js and update example.js local file snippet formatting.

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[tylertech-lee-hazlett]

@seantomburke this fixes #181