feat: Implement multi-tenancy with dynamic data source routing and introduce a database management UI.

frontend/admin/views/database.html

@@ -0,0 +1,73 @@
+<!-- ===== Database / Tenants Tab ===== -->
+
+<!-- Текущее подключение -->
+<div class="card">
+    <h2>Текущее подключение</h2>
+    <div id="db-status-info" class="db-status-card">
+        <div class="loading-row">Загрузка...</div>
+    </div>
+</div>
+
+<!-- Таблица тенантов -->
+<div class="card">
+    <h2>Подключённые университеты</h2>
+    <div class="table-wrap">
+        <table id="tenants-table">
+            <thead>
+                <tr>
+                    <th>Название</th>
+                    <th>Домен</th>
+                    <th>JDBC URL</th>
+                    <th>Пользователь</th>
+                    <th>Статус</th>
+                    <th>Действия</th>
+                </tr>
+            </thead>
+            <tbody id="tenants-tbody">
+                <tr>
+                    <td colspan="6" class="loading-row">Загрузка...</td>
+                </tr>
+            </tbody>
+        </table>
+    </div>
+</div>
+
+<!-- Добавить тенант -->
+<div class="card create-card">
+    <h2>Добавить подключение</h2>
+    <form id="add-tenant-form">
+        <div class="form-row">
+            <div class="form-group">
+                <label for="tenant-name">Название университета</label>
+                <input type="text" id="tenant-name" placeholder="ЮЗГУ" required>
+            </div>
+            <div class="form-group">
+                <label for="tenant-domain">Поддомен</label>
+                <input type="text" id="tenant-domain" placeholder="swsu" required>
+            </div>
+        </div>
+        <div class="form-row" style="margin-top: 0.75rem;">
+            <div class="form-group" style="flex: 3;">
+                <label for="tenant-url">JDBC URL</label>
+                <input type="text" id="tenant-url" placeholder="jdbc:postgresql://192.168.1.50:5432/magistr_db" required>
+            </div>
+        </div>
+        <div class="form-row" style="margin-top: 0.75rem;">
+            <div class="form-group">
+                <label for="tenant-username">Пользователь</label>
+                <input type="text" id="tenant-username" placeholder="postgres" required>
+            </div>
+            <div class="form-group">
+                <label for="tenant-password">Пароль</label>
+                <input type="password" id="tenant-password" placeholder="••••••••" required>
+            </div>
+            <button type="button" class="btn-primary" id="btn-test-connection" style="height: fit-content;">
+                Тест
+            </button>
+            <button type="submit" class="btn-primary" style="height: fit-content;">
+                Добавить
+            </button>
+        </div>
+        <div class="form-alert" id="add-tenant-alert" role="alert"></div>
+    </form>
+</div>