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/retrieve_asset.php

@@ -0,0 +1,19 @@
+<?php
+session_start();
+require_once '../../../assets/utils/db_auth.php';
+require_app_access('asset');
+require_once '../../../assets/utils/classes_as/AssetManager.php';
+
+try {
+    $answer['output']  = (new AssetManager($pdo2, $company_id))->getDetail((int)($data['id'] ?? 0));
+    $answer['success'] = 1;
+} catch (PDOException $e) {
+    error_log('[asset retrieve] ' . $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));