extractCalendarsAndEvents required a namespace prefix on <response>; Radicale
emits bare <response> (default DAV ns) so every entry was silently dropped —
REPORT 200, ok:true, 0 events, no error. Prefix is now optional in the split
and detection regexes.
Tests: 9 in the ns suite (extraction incl. mixed doc; empty multistatus;
namespace-aware fixture parse; undeclared element+attribute prefix rejection;
both quote styles; positive declared-attr case). Calendar-related suites: 52.
eslint clean.