Ajout des dates calculés

src/app/issues/issue-detail/issue-detail.html

@@ -155,15 +155,41 @@
         </div>
         <div class="row g-2">
           <div class="col-6">
-            <label class="field-label">Date de début</label>
-            <input
-              aria-label="Date de début"
-              class="form-control form-control-sm"
-              [class.is-invalid]="!!dateValidationError"
-              type="date"
-              [(ngModel)]="issue.startDate"
-              (blur)="onStartDateBlur()"
-            />
+            <div class="field-label-row">
+              <span class="field-label mb-0">Date de début</span>
+              @if (hasDependencies) {
+                <select
+                  class="date-mode-select"
+                  aria-label="Mode date de début"
+                  [ngModel]="issue.startDateMode"
+                  (ngModelChange)="startDateModeValue = $event"
+                >
+                  <option value="calculated">Calculée</option>
+                  <option value="forced">Forcée</option>
+                </select>
+              }
+            </div>
+            @if (issue.startDateMode === 'calculated') {
+              <input
+                aria-label="Date de début calculée"
+                class="form-control form-control-sm bg-body-secondary"
+                type="date"
+                [ngModel]="calculatedStartDate"
+                readonly
+              />
+              @if (startDateModeWarning) {
+                <div class="text-warning small mt-1">{{ startDateModeWarning }}</div>
+              }
+            } @else {
+              <input
+                aria-label="Date de début"
+                class="form-control form-control-sm"
+                [class.is-invalid]="!!dateValidationError"
+                type="date"
+                [(ngModel)]="issue.startDate"
+                (blur)="onStartDateBlur()"
+              />
+            }
           </div>
           <div class="col-6">
             <label class="field-label">Date de fin</label>