Add Asset Management app

Assets from purchase invoice lines, straight-line depreciation/amortization with salvage value, disposals, and [Asset Mgmt] sources in Batch GL Entries. Green third workspace with an app access guard.

app/asset/api/engine/manage_category.php

@@ -0,0 +1,22 @@
+<?php
+session_start();
+require_once '../../../assets/utils/db_auth.php';
+require_app_access('asset');
+require_role($user_role, ['owner', 'admin']);
+require_once '../../../assets/utils/classes_as/AssetCategoryManager.php';
+
+try {
+    $id = (new AssetCategoryManager($pdo2, $company_id))->save($data);
+    $answer['success'] = 1;
+    $answer['output']  = ['id' => $id];
+    $answer['message'] = !empty($data['id']) ? 'Category updated.' : 'Category created.';
+} catch (PDOException $e) {
+    error_log('[asset category] ' . $e->getMessage());
+    $answer['message'] = 'Database error, please try again.';
+    http_response_code(500);
+} catch (Exception $e) {
+    $answer['message'] = $e->getMessage();
+    http_response_code(400);
+}
+
+exit(json_encode($answer));