Add capacity insights to admin stats dashboard

[joelmeaders]

Summary

• surface capacity-by-day donut cards on the admin registration stats view and show totals inside the existing slot charts
• add FireRepoLite and PROGRAM_YEAR test helpers plus the missing modal/alert controller providers for the check-in review spec
• bump the workspace/admin/app packages to 2025.2.1 and capture the new work in the changelog

Testing

• Not run (not requested)

[github-actions]

Visit the preview URL for this PR (updated for commit 94772a3):

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[github-actions]

Visit the preview URL for this PR (updated for commit 94772a3):

https://santas-workshop-admin--pr129-admin-stats-znxv7ujk.web.app

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