Freezes a channel gated on Priv::Suspend: a typed Suspension on ChannelInfo
(event-logged, snapshotted, lazy expiry — same shape as the account one, no
Anope Extensible/Checker or expiry timer). While suspended, ChanServ refuses
all management (guards in require_op/require_founder and the founder-inline
SET/DROP/MLOCK), the engine skips Join enforcement (no auto-op/akick/entrymsg),
and suspending kicks everyone out; INFO shows it. parse_duration moved into the
SDK so both SUSPEND commands share it. Data + full-flow tests.