Add granular IPv6 disable option to setup scripts

Expanded IPv6 configuration in build.func to include a 'disable' option with clearer descriptions. Updated install.func to use IPV6_METHOD for disabling IPv6 via sysctl.d, improving clarity and control over IPv6 management.

misc/build.func

@@ -1445,11 +1445,12 @@ advanced_settings() {
       if result=$(whiptail --backtitle "Proxmox VE Helper Scripts [Step $STEP/$MAX_STEP]" \
         --title "IPv6 CONFIGURATION" \
         --ok-button "Next" --cancel-button "Back" \
-        --menu "\nSelect IPv6 Address Management:" 16 58 4 \
-        "auto" "SLAAC/AUTO (recommended)" \
-        "dhcp" "DHCPv6" \
-        "static" "Static (manual entry)" \
-        "none" "Disabled" \
+        --menu "\nSelect IPv6 Address Management:" 16 70 5 \
+        "auto" "SLAAC/AUTO (recommended) - Dynamic IPv6 from network" \
+        "dhcp" "DHCPv6 - DHCP-assigned IPv6 address" \
+        "static" "Static - Manual IPv6 address configuration" \
+        "none" "None - No IPv6 assignment (most containers)" \
+        "disable" "Fully Disabled - (breaks some services)" \
         3>&1 1>&2 2>&3); then
 
         _ipv6_method="$result"
@@ -1478,6 +1479,11 @@ advanced_settings() {
           _ipv6_gate=""
           ((STEP++))
           ;;
+        disable)
+          _ipv6_addr=""
+          _ipv6_gate=""
+          ((STEP++))
+          ;;
         none)
           _ipv6_addr="none"
           _ipv6_gate=""

misc/install.func

@@ -45,16 +45,24 @@ catch_errors
 # ------------------------------------------------------------------------------
 # verb_ip6()
 #
-# - Configures IPv6 based on DISABLEIPV6 variable
-# - If DISABLEIPV6=yes: disables IPv6 via sysctl
+# - Configures IPv6 based on IPV6_METHOD variable
+# - If IPV6_METHOD=disable: disables IPv6 via sysctl
 # - Sets verbose mode via set_std_mode()
 # ------------------------------------------------------------------------------
 verb_ip6() {
   set_std_mode # Set STD mode based on VERBOSE
 
-  if [ "$DISABLEIPV6" == "yes" ]; then
-    echo "net.ipv6.conf.all.disable_ipv6 = 1" >>/etc/sysctl.conf
-    $STD sysctl -p
+  if [ "$IPV6_METHOD" == "disable" ]; then
+    msg_info "Disabling IPv6 (this may affect some services)"
+    mkdir -p /etc/sysctl.d
+    $STD tee /etc/sysctl.d/99-disable-ipv6.conf >/dev/null <<EOF
+# Disable IPv6 (set by community-scripts)
+net.ipv6.conf.all.disable_ipv6 = 1
+net.ipv6.conf.default.disable_ipv6 = 1
+net.ipv6.conf.lo.disable_ipv6 = 1
+EOF
+    $STD sysctl -p /etc/sysctl.d/99-disable-ipv6.conf
+    msg_ok "Disabled IPv6"
   fi
 }