Add information, moderation, and sermon slide presentations as .pro
files in the generated .proplaylist bundle. Each block queries slides
by type/service, converts stored images, and generates a ProPresenter
presentation via ProFileGenerator.
Add test_download_pro_roundtrip_preserves_content that imports a .pro
file, exports it, re-reads with the parser, and asserts song name,
groups, slides, translations, arrangements, and CCLI metadata survive
the round-trip.
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