[WIP] Fix Lighthouse scores for performance and SEO

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>⚠️ Score Lighthouse sous le seuil acceptable</issue_title>
<issue_description>## 🔦 Alerte Performance / SEO

L'audit Lighthouse automatique a détecté des scores inférieurs aux seuils définis :

• Performance : minimum requis 60/100
• SEO : minimum requis 85/100

Workflow déclenché : 🔦 Lighthouse CI - Performance & SEO
Run ID : 24976199908

📊 Consultez les artefacts du workflow pour les rapports détaillés.

Issue créée automatiquement par le workflow Lighthouse CI.</issue_description>

<agent_instructions>Peux-tu corriger les erreurs @copilot </agent_instructions>

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@DavidKRK @copilot peut tu corriger stp ?

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