Change DTMF mode to auto for AX83H Android phone compatibility

AX83H may send DTMF as SIP INFO instead of RFC4733. Auto mode
accepts both, fixing button press detection in star code menus.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/asterisk/configmap.yaml

@@ -96,7 +96,7 @@ data:
     allow=ulaw
     allow=alaw
     direct_media=no
-    dtmf_mode=rfc4733
+    dtmf_mode=auto
     rtp_symmetric=yes
     force_rport=yes
     rewrite_contact=yes