feat: Add user edit modal and user management pages

- Implemented user edit modal in user_edit.html for editing user details.
- Updated sidebar.html to correctly reflect active states for Users and Settings.
- Created table-07.html for displaying user data in a structured format.
- Added settings.html for managing email content and configurations.
- Developed users.html for listing all users with functionality to add and edit users.

api/users/delete.php

@@ -0,0 +1,48 @@
+<?php
+require "../api.php";
+
+$api = new spamhasiApi();
+$conf = $api->getConf();
+
+if (!$api->checkAuth()) {
+    die('{"status":500, "error":"Unauthorized"}');
+}
+
+if (!isset($_POST["id"])) {
+    die('{"status":500, "error":"Missing fields"}');
+}
+
+$id = intval($_POST["id"]);
+
+$db = $api->getDB();
+
+$sql = "SELECT COUNT(*) FROM users";
+$stmt = $db->query($sql);
+
+$count = $stmt->fetchColumn();
+
+if ($count == 1) {
+    die('{"status":500, "error":"Der einzige Benutzer darf NICHT GELÖSCHT WERDEN!"}');
+}
+
+$sql = "SELECT username FROM users WHERE id = :id";
+$stmt = $db->prepare($sql);
+$stmt->execute([':id' => $id]);
+$result = $stmt->fetch(PDO::FETCH_ASSOC);
+$name = $result["username"];
+
+$sql = "DELETE FROM users WHERE id = :id";
+$stmt = $db->prepare($sql);
+
+$sql_exec = $stmt->execute([':id' => $id]);
+
+if (!$sql_exec) {
+    die('{"status":500, "error":"SQL Error"}');
+}
+
+if (!unlink($conf["PATH"] . "/tmp/user_sessions/" . $name . ".json")) {
+    die('{"status":500, "error":"Error to remove session file."}');
+}
+
+die('{"status":200}');
+?>