fix(telephony): stop ARI WebSocket false-abort loop (pong-timeout 15s->3600s)

Asterisk res_http_websocket does not reliably answer client PING frames
with PONG, so .NET KeepAliveTimeout (default 15s) aborted a healthy idle
ARI WebSocket every ~45s (ping@30s + pong-wait@15s), dropping StasisStart
events so the *100 IVR intermittently answered with no audio. Generous pong
timeout stops the false aborts; genuine drops still caught by the 45s
receive-timeout state re-check and TCP-level WebSocketException.

Surfaced by FlowerCore.Telephony.SipTests Call_Star100_ReceivesAudibleAudioStream
(0 RTP packets while ExtToExt RTP-hook passed).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/telephony/telephony.yaml

@@ -62,7 +62,10 @@ data:
         "Password": "bluejay-asterisk-ari",
         "Application": "flowercore-pbx",
         "ReconnectDelaySeconds": 5,
-        "MaxReconnectDelaySeconds": 60
+        "MaxReconnectDelaySeconds": 60,
+        "WebSocketKeepAliveIntervalSeconds": 30,
+        "WebSocketKeepAliveTimeoutSeconds": 3600,
+        "WebSocketReceiveTimeoutSeconds": 45
       },
       "Sip": {
         "Domain": "10.0.56.207",