Fix: install ffmpeg, rsync, sox and add fallback copy in BackupManager for sound extraction

install.sh

@@ -58,7 +58,10 @@ apt-get install -y --no-install-recommends \
     ca-certificates \
     iptables \
     iptables-persistent \
-    acl
+    acl \
+    ffmpeg \
+    rsync \
+    sox
 
 # Vérification et installation d'Asterisk
 echo -e "${C_GREEN}  -> Installation du moteur Asterisk PBX...${C_RESET}"