Add About page and navigation link

[DigiEuro]

Summary

• add a dedicated About page describing the MiCAR Tracker and DEA leadership using existing card styling
• include navigation entry for About directly after the Non-Compliant button to match existing header buttons
• update Tailwind configuration so the new page is included in the content purge list

Testing

• npm run build:css

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Codex Task

[chatgpt-codex-connector]

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