chore: migrate internal schemas package to npm-hosted package

[JoshMock]

I'm working on a standalone package for storing all Zod schemas. This removes the bundled package and depends on that package. Not ready to merge until @elastic/schemas is published to npm.

Major changes:

• packages/es-schemas/ no longer exists; imports @elastic/schemas instead
• Zod dependency is removed in favor of ajv

Results:

• npm pack (gzip of compiled source) size reduced from 26MB to 18MB
• speed benchmarks: equivalent
• heap usage benchmarks: equivalent

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	1		0	0	0.25s
✅ COPYPASTE	jscpd	yes		no	no	0.59s
✅ REPOSITORY	gitleaks	yes		no	no	61.58s
✅ REPOSITORY	git_diff	yes		no	no	0.07s
✅ REPOSITORY	secretlint	yes		no	no	3.21s
✅ REPOSITORY	trivy	yes		no	no	20.84s
✅ TYPESCRIPT	eslint	58		0	0	9.07s
✅ YAML	yamllint	2		0	0	0.83s

Notices

📣 MegaLinter 9.5.0 is out! Discover the new features and security recommendations in the release announcement. (Skip this info by defining SECURITY_SUGGESTIONS: false)

See detailed reports in MegaLinter artifacts
Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff

MegaLinter is graciously provided by OX Security
Show us your support by starring ⭐ the repository

[github-actions]

🔍 Preview links for changed docs

• ARCHITECTURE.md
• packages/es-schemas/CHANGELOG.md