inspircd: include membid in outbound IJOIN

Services IJOIN was ':<uid> IJOIN <chan>' with no membership id, but InspIRCd
requires <chan> <membid> (min 2 params). On link the ircd rejected the whole
server connection with 'Insufficient parameters' the moment a BotServ bot joined
its assigned channel, splitting services. Add a monotonic membid, matching how
InspIRCd itself sends IJOIN. Validated against a real InspIRCd 4 with production
data: full burst to ENDBURST, all bot IJOINs accepted, no split.

.gitignore

@@ -11,3 +11,9 @@ fedserv.db.jsonl
 /demo-stop.sh
 /test-net
 /test-net-b
+
+# Runtime data/logs
+echo.db.jsonl
+cutover-echo.log
+test-net/echo.db.jsonl
+test-net/*.log