Enable search and OG images with Fumadocs

[torn4dom4n]

This PR enables search and Open Graph (OG) images using Fumadocs' built-in features.

Key changes:

• Created a search API route at app/api/search/route.ts using createFromSource, enabling the documentation search dialog.
• Updated app/og/route.tsx to utilize generateOGImage from fumadocs-ui/og for consistent and professional social media previews.
• Refactored metadata generation in app/[[...slug]]/page.tsx to automatically link pages to their generated OG images.
• Adapted the implementation for Fumadocs v16 by removing the deprecated createMetadataImage helper and handling image parameters manually.

Verification:

• Verified that the /api/search endpoint returns correct results.
• Verified that OG images are correctly generated and metadata is correctly applied to documentation pages using Playwright.
• Build and lint checks passed successfully.

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PR created automatically by Jules for task 1410171931120829090 started by @torn4dom4n

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