Add OperServ with AKILL network bans

The first operator module. AKILL manages network bans as a typed,
event-sourced list with lazy expiry, mirroring the patterns the other
modules use:

- AKILL ADD [+expiry] <user@host> <reason> stores the ban and drives an
  ircd G-line (applied to matching users already online and to future
  connections); AKILL DEL <mask|number> lifts it; AKILL LIST [pattern]
  shows the live list, numbered. Admin-only.
- Bans are Global events, so every node holds the list and re-asserts each
  one at burst with its remaining duration. Expired bans are hidden lazily
  and dropped at compaction.
- Masks are normalised to user@host (a nick! prefix is stripped, both
  sides lowercased) and an all-wildcard mask is refused.

Email (send_email) is already reachable from the api via ServiceCtx, and
adds AddLine/DelLine to the action vocabulary for any future X-line kinds.

src/grpc.rs

@@ -164,7 +164,9 @@ fn to_wire(entry: &LogEntry) -> Option<ReplicationEvent> {
         | Event::AccountSeen { .. }
         | Event::ChannelUsed { .. }
         | Event::AccountNoExpire { .. }
-        | Event::ChannelNoExpire { .. } => return None,
+        | Event::ChannelNoExpire { .. }
+        | Event::AkillAdded { .. }
+        | Event::AkillRemoved { .. } => return None,
     };
     Some(ReplicationEvent { origin: entry.origin().to_string(), seq: entry.seq(), lamport: entry.lamport(), kind: Some(kind) })
 }