cdr: store Cdr events, aggregate calls, fixtures from real calls

services/cdr.ts stores every AMI Cdr event in cdr and, 5 s after a
call's last event, builds its calls row (direction, status, from, to,
DID, answered by, talk time) and call_extensions (caller, rang,
answered) per 04 §5.4; linkedids without a calls row are caught up on
AMI connect. Aggregation is idempotent.

test/asterisk/cdr-record.ts records 8 scenarios with our config, the
fake voip.ms (now shared in provider.ts) and baresip phones; each has a
fixture and a test with the expected calls row. Queue abandon and park
come with M8.

Found while recording: Asterisk 24's Cdr event has no LinkedID unless
cdr_manager maps it, its times carry no zone (now usegmtime), and the
mappings read CDR variables, so the dialplan sets CDR(SP_DID) and
CDR(SP_DIRECTION) next to the channel variables. The Asterisk image
needs a rebuild for the cdr_manager.conf change.

Task: M7-T1

asterisk/conf/cdr_manager.conf

@@ -1,6 +1,9 @@
 [general]
 enabled = yes
+usegmtime = yes            ; times in UTC: the api parses them without guessing a time zone
+
 [mappings]
+linkedid => LinkedID       ; groups every leg of one call (04 §5.4); not in the event by default
 SP_DID => sp_did
 SP_DIRECTION => sp_direction
 SP_REC => sp_recording