pub const IMG_SLOT_PLACEHOLDER_URI: &str = "data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%20600%20400%22%3E%3Crect%20width%3D%22600%22%20height%3D%22400%22%20fill%3D%22%23e5e9f0%22%2F%3E%3Ccircle%20cx%3D%22410%22%20cy%3D%22130%22%20r%3D%2242%22%20fill%3D%22%23c9d2e0%22%2F%3E%3Cpath%20d%3D%22M0%20400%20210%20180%20330%20310%20420%20230%20600%20400z%22%20fill%3D%22%23c9d2e0%22%2F%3E%3C%2Fsvg%3E";Expand description
Placeholder image for unresolved «IMG:» slots: a self-contained SVG data
URI (neutral surface, sun + mountains glyph).
Guaranteed free of ", ', &, and < so it splices verbatim into
src="…", url('…'), and url("…") contexts. Style chunks may swap the
SVG body but MUST keep that guarantee (percent-encode everything).