Fix kiosk audio output: don't mute microphone by default

The PTT handler was muting the audio source before checking if a PTT
device was configured. This prevented kiosks from sending audio back
to calling phones during normal intercom operation.

Changes:
- Move audio mute command after PTT device check
- Only mute audio when PTT device is actually configured
- Leave audio unmuted for standard kiosk intercom functionality
- Add clarifying comments about PTT mode vs normal operation

This fixes the issue where phones calling the kiosk could send audio
but received no audio back from the kiosk.

easy-asterisk-interactive-v1.28.sh

@@ -959,9 +959,11 @@ CONFIG="/etc/easy-asterisk/config"
 PTT_CONFIG="/etc/easy-asterisk/ptt-device"
 [[ -f "$CONFIG" ]] && source "$CONFIG"
 [[ -f "$PTT_CONFIG" ]] && source "$PTT_CONFIG"
+
+# Exit if no PTT device configured - leave audio unmuted for normal kiosk operation
 [[ -z "$PTT_DEVICE" ]] && exit 0
 
-# Default: Mute audio source on start
+# PTT mode: Mute audio source on start, unmute only when button pressed
 pactl set-source-mute @DEFAULT_SOURCE@ 1
 
 # Unmute on press, mute on release