feat(helpdesk): align module with core list/drawer standards

- add helpdesk module pages, services, settings and tests

- standardize debtor list on drawer/grid contracts and robust filter drawer behavior

- add helpdesk aside panel navigation and settings visibility provider

- switch primary list slug to helpdesk/debitor and remove helpdesk/search compatibility

- include required core contract updates for list contracts and detail/drawer integration

web/css/components/app-details.css

@@ -1,6 +1,6 @@
 @layer components {
   /* Detail page layout — aside panel, card sections, sticky titlebar integration. */
-  .app-details-container aside {
+  .app-details-container > aside {
     padding-top: var(--app-spacing);
   }
 
@@ -150,7 +150,7 @@
     padding: calc(var(--app-spacing) * 2) calc(var(--app-spacing) * 2)
       calc(var(--app-spacing) * 2) calc(var(--app-spacing) * 0);
   } */
-    .app-details-container:has(aside) {
+    .app-details-container:has(> aside) {
       display: grid;
       grid-template-columns: minmax(0, 2fr) minmax(0, 300px);
       min-height: 82vh;
@@ -158,10 +158,10 @@
     .app-details-container.is-aside-collapsed {
       grid-template-columns: minmax(0, 1fr);
     }
-    .app-details-container.is-aside-collapsed aside {
+    .app-details-container.is-aside-collapsed > aside {
       display: none;
     }
-    .app-details-container aside {
+    .app-details-container > aside {
       border-left: 1px solid var(--app-border);
       padding: calc(var(--app-spacing) * 2);
       border-top: none;