feature: Add share button for compare results

[O2sa]

Users should be able to share a completed comparison with others from the compare results page. The app already encodes compared usernames and selected languages in the query string, but the result dashboard only has a Copy Result action that copies the raw JSON payload instead of a shareable link.

Context

• components/home-page-client.tsx updates the URL with username and selectedLanguage params when a comparison runs.
• components/result-dashboard.tsx already has a result action area with a clipboard-based Copy Result button.
• components/result-dashboard.tsx uses useSearchParams() to preserve comparison context for the methodology link, so the same URL context can be reused for sharing.
• locales/en.json and locales/ar.json currently include copy-result labels but no share labels.

Tasks

• Add a share button to the compare results action area in components/result-dashboard.tsx.
• Build the share URL from the current origin/path and active comparison query params, including selected languages.
• Use the Web Share API (navigator.share) when available, with a clipboard fallback for unsupported browsers.
• Add localized labels, aria labels, and success/failure feedback for English and Arabic.
• Verify the shared URL reloads the same comparison without requiring manual input.

Tip

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