feat: add media management section

[everpcpc]

Summary

• Add Media management section to server admin tools, replicating Komga web UI sidebar functionality
• Media Analysis: filter books by error/unsupported status with inline library toggles (All Libraries + per-library)
• Missing Posters: browse books without selected poster thumbnails
• Duplicate Files: books grouped by file hash with thumbnails, paths, and size info
• Duplicate Pages: Known (with action badges, space metrics, delete/action controls) and Unknown (with bulk actions)
• Page Hash Matches: view and delete individual matches with page thumbnails
• Full localization for all 10 supported languages
• Prevent unnecessary data reload when returning from detail navigation

Closes #545

Test plan

• Verify Media tile appears in Server management section (admin only)
• Media Analysis: toggle Error/Unsupported filters, toggle library selection, verify pagination
• Missing Posters: verify book list loads with thumbnails
• Duplicate Files: verify books are grouped by hash, Load More works
• Duplicate Pages Known: filter by action type, view matches sheet, change actions, delete matches
• Duplicate Pages Unknown: mark individual hashes, bulk actions work
• Navigate to book detail and back — verify no unnecessary reload
• Pull to refresh works on all views
• Test on iOS, macOS, tvOS

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