feat: Implement floors, locations, and racks management

- Added list, edit, and save functionalities for floors, locations, and racks.
- Enhanced UI with search and filter options for better usability.
- Implemented SVG upload for floor plans in the floors module.
- Added validation for required fields in the save processes.
- Improved navigation in the header to reflect new modules.
- Styled forms and tables for a consistent look and feel across modules.

app/modules/racks/save.php

@@ -0,0 +1,73 @@
+<?php
+/**
+ * app/modules/racks/save.php
+ *
+ * Speichert / aktualisiert ein Rack
+ */
+
+// Nur POST
+if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
+    header('Location: ?module=racks&action=list');
+    exit;
+}
+
+// =========================
+// Daten einlesen
+// =========================
+$rackId = (int)($_POST['id'] ?? 0);
+$name = trim($_POST['name'] ?? '');
+$floorId = (int)($_POST['floor_id'] ?? 0);
+$heightHe = (int)($_POST['height_he'] ?? 42);
+$comment = trim($_POST['comment'] ?? '');
+
+// =========================
+// Validierung
+// =========================
+$errors = [];
+
+if (empty($name)) {
+    $errors[] = "Name ist erforderlich";
+}
+
+if ($floorId <= 0) {
+    $errors[] = "Stockwerk ist erforderlich";
+}
+
+if ($heightHe < 1) {
+    $errors[] = "Höhe muss mindestens 1 HE sein";
+}
+
+// Falls Fehler: zurück zum Edit-Formular
+if (!empty($errors)) {
+    $_SESSION['error'] = implode(', ', $errors);
+    $redirectUrl = $rackId ? "?module=racks&action=edit&id=$rackId" : "?module=racks&action=edit";
+    header("Location: $redirectUrl");
+    exit;
+}
+
+// =========================
+// In DB speichern
+// =========================
+if ($rackId > 0) {
+    // UPDATE
+    $sql->set(
+        "UPDATE racks SET name = ?, floor_id = ?, height_he = ?, comment = ? WHERE id = ?",
+        "siisi",
+        [$name, $floorId, $heightHe, $comment, $rackId]
+    );
+} else {
+    // INSERT
+    $sql->set(
+        "INSERT INTO racks (name, floor_id, height_he, comment) VALUES (?, ?, ?, ?)",
+        "sii s",
+        [$name, $floorId, $heightHe, $comment]
+    );
+}
+
+$_SESSION['success'] = "Rack gespeichert";
+
+// =========================
+// Redirect
+// =========================
+header('Location: ?module=racks&action=list');
+exit;