- ||text|| in outgoing messages/edits becomes <span data-mx-spoiler> (MSC2010),
matching what Blap Android sends; code/pre spans are left alone
- spoiler media uploads get the Discord SPOILER_ filename prefix (the only
marker the Rust SDK on Android can produce) and isSpoilerMedia honors it
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>