detail: always show the subtasks group so add is reachable

Render the subtasks group on every task, not just ones that already
have children, so the inline add field is available from the start.
Hide the done/total count until there's at least one subtask.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/java/de/jeanlucmakiola/floret/ui/detail/TaskDetailScreen.kt

@@ -266,8 +266,8 @@ private fun DetailBody(
             }
 
             // Subtasks — a genuine group: a connected grouped run whose first
-            // segment is the expand/collapse toggle.
+            // segment is the expand/collapse toggle. Always shown (even with no
-            if (detail.subtasks.isNotEmpty()) {
+            // subtasks yet) so the add field is reachable on any task.
             add {
                 SubtasksGroup(
                     subtasks = detail.subtasks,
@@ -279,7 +279,6 @@ private fun DetailBody(
                 )
             }
         }
-        }
         cards.forEachIndexed { index, card ->
             if (index > 0) Spacer(Modifier.height(gap))
             card()
@@ -326,12 +325,15 @@ private fun SubtasksGroup(
                 style = MaterialTheme.typography.titleMedium,
                 modifier = Modifier.weight(1f),
             )
+            // No count until there's something to count.
+            if (subtasks.isNotEmpty()) {
                 Text(
                     text = "$done / ${subtasks.size}",
                     style = MaterialTheme.typography.labelLarge,
                     color = MaterialTheme.colorScheme.onSurfaceVariant,
                 )
                 Spacer(Modifier.width(8.dp))
+            }
             Icon(
                 imageVector = Icons.Rounded.ExpandMore,
                 contentDescription = null,