/// The viewer HTML template. Placeholders are replaced by `compile_html`:
/// - `{{MANIFEST_JSON}}` — serialized ViewerManifest as JSON
/// - `{{AUDIO_BASE64}}` — Opus audio file encoded as Base64
/// - `{{SLIDE_SCRIPTS}}` — `<script type="text/xml" id="slide-N">` blocks
pub const TEMPLATE: &str = include_str!;