fix(leads): keep a future follow-up as an activity on the lead

A scheduled follow-up only stored a date, and activities opened from a lead were not linked back, so they disappeared from the lead.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/web/src/views/LeadDetailView.vue

@@ -845,6 +845,16 @@ onBeforeUnmount(() => narrowMq?.removeEventListener('change', syncNarrow));
                     </template>
                   </a-list>
                   <a-empty v-else description="فعالیت مرتبطی نیست." />
+                  <RouterLink
+                    :to="{ name: 'activity-new', query: { leadId: lead.id } }"
+                    custom
+                    v-slot="{ navigate }"
+                  >
+                    <a-button type="dashed" block @click="navigate">
+                      <template #icon><PlusOutlined /></template>
+                      ایجاد فعالیت
+                    </a-button>
+                  </RouterLink>
 
                   <a-divider orientation="right">جدول زمانی</a-divider>
                   <a-timeline v-if="lead.events.length">
@@ -889,17 +899,6 @@ onBeforeUnmount(() => narrowMq?.removeEventListener('change', syncNarrow));
                       مشاهده همه فعالیت‌ها
                     </a-button>
                   </RouterLink>
-                  <RouterLink
-                    v-if="narrow"
-                    :to="{ name: 'activity-new' }"
-                    custom
-                    v-slot="{ navigate }"
-                  >
-                    <a-button type="dashed" block @click="navigate">
-                      <template #icon><PlusOutlined /></template>
-                      ایجاد فعالیت
-                    </a-button>
-                  </RouterLink>
                 </template>
               </a-card>