Preserve file path case in file manager UI

[ZacharyZcR]

Summary

• Preserve the original case of file editor titles instead of uppercasing filenames
• Preserve the original case of the file path shown in file properties/permissions

Fixes Termix-SSH/Support#860

Verification

• npx prettier --check src/ui/features/file-manager/components/DraggableWindow.tsx src/ui/features/file-manager/components/PermissionsDialog.tsx
• npx eslint src/ui/features/file-manager/components/DraggableWindow.tsx src/ui/features/file-manager/components/PermissionsDialog.tsx
• npm run type-check
• git diff --check

Build note

• npm run build still fails before this change completes because src/ui/index.css cannot resolve @fontsource/jetbrains-mono/400.css in the current checkout.