Gslmao/pdf viewer new

[Gslmao]

📌 Purpose

Migrates the PDF viewer from react-pdf to embedpdf with the Pdfium WASM engine for improved rendering performance and a more modular plugin architecture.

Corresponding issue: closes #472

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🖼️ Showcase

Desktop View

Desktop view fullscreen

Mobile View

Mobile View Fullscreen

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🔧 Changes

• Engine: Swapped react-pdf for embedpdf with viewport, scroll, zoom, render, document manager, and export plugins.
• Scroll & Zoom: Removed manual pageRefs scroll tracking, offsetTop math, and the wheel event handler.
• Toolbar: Extracted into a standalone memoised Controls component. Added a useBreakpoint hook to handle responsive layout, consolidating the three previously duplicated toolbar variants (mobile, desktop, fullscreen) into one component with a resolved layout per breakpoint.
• Performance: toggleFullscreen, handleDownload, and the plugins array are all stabilised with useCallback/useMemo to prevent unnecessary re-renders of the memoised Controls.

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➕ Additional Notes

• The flickering of the pages when zooming and in and out was fixed