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/ac_dashboard/index.php

@@ -199,7 +199,11 @@
     supplier_credit_note: 'Supplier Credit Note',
     receipt:              'Receipt',
     payment:              'Payment',
-    manual:               'Manual'
+    manual:               'Manual',
+    asset_capitalization: 'Asset Mgmt · Capitalization',
+    asset_depreciation:   'Asset Mgmt · Depreciation',
+    asset_amortization:   'Asset Mgmt · Amortization',
+    asset_disposal:       'Asset Mgmt · Disposal'
   };
 
   var source_badges = {
@@ -209,7 +213,11 @@
     supplier_credit_note: 'bg-secondary-subtle text-secondary',
     receipt:              'bg-info-subtle text-info',
     payment:              'bg-danger-subtle text-danger',
-    manual:               'bg-dark-subtle text-dark'
+    manual:               'bg-dark-subtle text-dark',
+    asset_capitalization: 'bg-success text-white',
+    asset_depreciation:   'bg-success text-white',
+    asset_amortization:   'bg-success text-white',
+    asset_disposal:       'bg-success text-white'
   };
 
   function fmt_num(n) {