Delete-FTP-User Button und Fix für sudoers-Pfad

- Plugin: Neuer "Delete FTP User" Button im FTP-User-Bereich
  - Mit Bestätigungsdialog
  - Löscht nur FTP-Account + Bind-Mounts, System-User bleibt unberührt
- Helper-Script: neues 'deluser' Kommando
- sudoers-Fix: tee für /etc/pure-ftpd/* (statt nur conf/*) —
  cmd_passwd muss nach /etc/pure-ftpd/pureftpd.passwd schreiben können,
  das war vorher nicht erlaubt und führte zu 'Failed to create FTP user'
  beim Anlegen weiterer User

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/dolphin-ftp-share

@@ -92,7 +92,8 @@ ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/mount --bind *
 ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/mount -o remount?ro?bind *
 ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/umount ${REAL_FTP_ROOT}/*
 ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/pure-pw *
-${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/tee /etc/pure-ftpd/conf/*
+${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/tee /etc/pure-ftpd/*
+${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/tee -a /etc/pure-ftpd/*
 ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/rm -f /etc/pure-ftpd/conf/PassivePortRange
 ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/sed -i *pureftpd.passwd*
 ${REAL_USER} ALL=(root) NOPASSWD: /usr/bin/systemctl restart pure-ftpd
@@ -229,6 +230,38 @@ cmd_passwd() {
     rebuild_db
 }
 
+cmd_deluser() {
+    local username="$1"
+
+    if [ -z "$username" ]; then
+        echo "Error: username is required" >&2
+        exit 1
+    fi
+
+    # Unmount all shares from this user's root first
+    local user_root="$FTP_ROOT/users/$username"
+    if [ -d "$user_root" ]; then
+        for mp in "$user_root"/*/; do
+            [ -d "$mp" ] || continue
+            if mountpoint -q "$mp" 2>/dev/null; then
+                sudo umount "$mp"
+            fi
+            rmdir "$mp" 2>/dev/null || true
+        done
+        rmdir "$user_root" 2>/dev/null || true
+    fi
+
+    # Remove user entry from passwd file
+    if sudo pure-pw show "$username" -f "$PASSWD_FILE" >/dev/null 2>&1; then
+        sudo sed -i "/^${username}:/d" "$PASSWD_FILE"
+        rebuild_db
+        echo "FTP user '$username' deleted"
+    else
+        echo "FTP user '$username' does not exist"
+        exit 1
+    fi
+}
+
 cmd_serverconfig() {
     local action="$1"
 
@@ -276,9 +309,10 @@ case "${1:-}" in
     delete)       cmd_delete "$2" ;;
     userexists)   cmd_userexists "$2" ;;
     passwd)       cmd_passwd "$2" "$3" ;;
+    deluser)      cmd_deluser "$2" ;;
     serverconfig) cmd_serverconfig "$2" "$3" "$4" ;;
     *)
-        echo "Usage: dolphin-ftp-share {setup|info|add|delete|userexists|passwd|serverconfig}" >&2
+        echo "Usage: dolphin-ftp-share {setup|info|add|delete|userexists|passwd|deluser|serverconfig}" >&2
         echo "" >&2
         echo "Commands:" >&2
         echo "  setup                             Initial Pure-FTPd setup" >&2
@@ -287,6 +321,7 @@ case "${1:-}" in
         echo "  delete <name>                     Remove a share" >&2
         echo "  userexists <username>              Check if FTP user exists" >&2
         echo "  passwd <username> <password>       Set/create FTP password" >&2
+        echo "  deluser <username>                 Delete FTP user (not system user)" >&2
         echo "  serverconfig show                  Show current server config" >&2
         echo "  serverconfig active                Set active mode" >&2
         echo "  serverconfig passive <start> <end> Set passive mode with port range" >&2