chore: percy visual regression tests

[stephiescastle]

Checklist

• Include a description of your pull request and instructions for the reviewer to verify your work.
• Link to the issue if this PR is issue-specific.
• Create/update the corresponding story if this includes a UI component.
• Create/update documentation. If not included, tell us why.
• List the environments / browsers in which you tested your changes.
• Tests, linting, or other required checks are passing.
• PR has an informative and human-readable title
  • PR titles are used to generate the change log in releases; good ones make that easier to scan.
  • PRs will be broadly categorized in the change log, but for even easier scanning, consider prefixing with a component name or other useful categorization, e.g., "BaseButton: fix layout bug", or "Storybook: Update dependencies".
• PR has been tagged with a SemVer label and a general category label, or skip-changelog.
  • These tags are used to do the aforementioned broad categorization in the change log and determine what the next release's version number should be.
  • Release Drafter will attempt to do the category labeling for you! Please double-check its work.

Description

Completes https://github.com/nasa-jpl/www/issues/188

• Removes Chromatic visual regression tests (no quota) and adds percy visual regression tests to our CI.
• Check /apps/vue-storybook/.percy.yml to see a list of included/excluded stories. We may continue to refine this depending on how our quota usage goes.

Instructions to test

1. pnpm install
2. make vue-storybook-build
3. pnpm --filter @explorer-1/vue-storybook percy:dry-run

[stephiescastle]

Link to percy tests: https://percy.io/e5a03e0a/explorer-1/builds/35608683

Note: this generated 1434 snapshots and used ~5% of our quota. Seems a bit high, so I might remove firefox snapshots since @Scotchester and I regularly use the site in Firefox. I think we need to keep Safari snapshots, though. This should reduce snapshots by a third.

[stephiescastle]

Note, I canceled the last test action to not needlessly use up our quota.