[codex] Prepare 2.0.0 beta prerelease

[hackjutsu]

Summary

Prepares the repository for the v2.0.0-beta.1 prerelease tag.

• Bumps package.json to 2.0.0-beta.1.
• Updates the root package version in package-lock.json.
• Regenerates license.json so the root Lepton@... entry matches the prerelease version.

Validation

• npm run lint
• npm test - 142 Vitest tests plus webpack development build
• npm run test:packaged-smoke - unsigned packaged app rendered login and fixture surfaces
• ruby -e "require 'yaml'; YAML.load_file('.github/workflows/release.yml'); puts 'release workflow yaml ok'"
• git diff --check

Tagging

After this PR merges to master, create and push the prerelease tag:

git checkout master
git pull origin master
git tag v2.0.0-beta.1
git push origin v2.0.0-beta.1

That tag will trigger the Release workflow as a GitHub prerelease and Snap edge publish.