Add package-lock.json and switch CI to npm ci for validate workflow

[GsCommand]

Motivation

• The validate CI job was changed to use npm ci but the repository had no package-lock.json, causing CI failures.
• Provide a lockfile so npm ci can install reproducibly without changing declared dependencies.

Description

• Add a generated package-lock.json for the current package so CI has a lockfile to consume.
• Remove package-lock.json from .gitignore so the lockfile can be tracked (.gitignore updated).
• Ensure the validate workflow uses npm ci for installation (.github/workflows/validate.yml updated).
• Files changed: package-lock.json, .gitignore, and .github/workflows/validate.yml.

Testing

• Ran npm install --package-lock-only to generate the lockfile (succeeded).
• Ran npm ci against the repo using the new lockfile (succeeded).
• Ran npm run validate which executes schema and example validation (all validations succeeded).
• git diff --check was run to ensure no whitespace/patch issues (no problems found), and the validate workflow should now pass using npm ci because a committed package-lock.json is present.

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Codex Task