Restore working slide rewrite + short AI feature from commit 74ca420b: simpler _oembed_probe without broken YouTube metadata fallback, working makeWallItem without isEmbed/embed_oembed bug, correct cache-buster in index_v2.html
Restore working slide rewrite + short AI feature from commit 74ca420b: simpler _oembed_probe without broken YouTube metadata fallback, working makeWallItem without isEmbed/embed_oembed bug, correct cache-buster in index_v2.html