fix: make Caddyfile global config update robust to avoid IPv6 conflicts

src/core.sh

@@ -159,15 +159,18 @@ update_caddyfile_fallback() {
     sed -i 's/servers :443/servers :4443/g' $is_caddyfile
     
     # 2. Replace any site block headers explicit :443 with :4443
-    sed -i 's/:443[[:space:]]*{/:4443 {/g' $is_caddyfile
+    sed -i 's/:443\b/:4443/g' $is_caddyfile
     
-    # 3. Add or update https_port 4443 in global block
-    if [[ $(grep "https_port" $is_caddyfile) ]]; then
+    # 3. Add or update https_port 4443 globally
+    if grep -q "https_port" $is_caddyfile; then
         # Replace existing https_port with 4443
         sed -i 's/https_port[[:space:]]\+[0-9]\+/https_port 4443/g' $is_caddyfile
-    else
-        # Find first { and insert https_port 4443 on the next line
+    elif grep -q '^[[:space:]]*{[[:space:]]*$' $is_caddyfile; then
+        # Insert inside existing global block
         sed -i '0,/^[[:space:]]*{[[:space:]]*$/s//{\n  https_port 4443/' $is_caddyfile
+    else
+        # Prepend a new global block at the very top of the Caddyfile
+        echo -e "{\n  https_port 4443\n}\n$(cat $is_caddyfile)" >$is_caddyfile
     fi
 }