Refactor work time management and billing summary

- Introduced a new `TasksController` to handle work time logic, moving it from the factory layer to the domain layer.
- Created `WorkTimeRepository` to encapsulate data access for work time tasks, including methods to retrieve clients with unsettled tasks and calculate task times.
- Updated the work time view to display a consolidated billing summary with improved UI elements and AJAX functionality for closing tasks.
- Added new styles for the billing summary section in `style.scss`.
- Implemented tests for the `TasksController` and `WorkTimeRepository` to ensure functionality and correctness.
- Established a refactoring plan for future improvements and migrations within the CRM system.

layout/style.scss

@@ -1537,4 +1537,46 @@ body>.top {
     flex: 1;
     max-width: calc(100% - 350px);
   }
+}
+
+#billing-summary {
+  .card-header {
+    padding: 10px;
+  }
+
+  .billing-kpi {
+    border: 1px solid #dee2e6;
+    border-radius: 6px;
+    padding: 10px 12px;
+    background: #ffffff;
+    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
+  }
+
+  .billing-kpi-label {
+    font-size: 12px;
+    color: #6c757d;
+    margin-bottom: 3px;
+  }
+
+  .billing-kpi-value {
+    font-size: 21px;
+    font-weight: 700;
+    line-height: 1.1;
+  }
+
+  .billing-details-row {
+    display: none;
+  }
+
+  .billing-client-name {
+    font-weight: 600;
+  }
+
+  .billing-table>thead>tr>th {
+    background: #f8f9fa;
+  }
+
+  .billing-details-wrap {
+    background: #f8fbff;
+  }
 }