Add usage statistics cards to user gitlab credits dashboard

What does this MR do and why?

Add usage statistics cards to user gitlab credits dashboard, using mocked data under a feature flag.

References

• Issue: #605991
• Epic: gitlab-org#22817
• Prototype: https://product-rapidprototype-a1c47d.gitlab.io/self-scoped-credits-usage/
• MR Cadence:

MR	Description
!246133 (merged)	Add /-/profile/gitlab_credits_dashboard initial view
!246138 (merged)	Add user credits dashboard shell app
!246157 (merged)	Add total credits used card to user gitlab credits dashboard
!246173 (merged)	Add filters to user gitlab credits dashboard
!246180	👈 you're here
!246189	Add consumption chart to user gitlab credits dashboard

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Ensure you're running local GDK in SAAS mode (e.g. export GITLAB_SAAS=1 gdk restart)
• Enable user_gitlab_credits_dashboard
• Visit http://gdk.test:3000/-/profile/gitlab_credits_dashboard

Or

• yarn storybook:start
• Visit http://localhost:6006/?path=/story/ee-usage-quotas-user-credits-dashboard-app--default

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.