fix: Task back button navigates to correct recipe (not version_id)

- Add recipe_id property to RecipeTask model (via version relationship)
- Add recipe_id to TaskResponse schema
- Eager-load version in _get_task_or_404 query
- Use task.recipe_id instead of task.version_id in task_execute template URLs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/templates/measure/task_execute.html

@@ -72,7 +72,7 @@
         <div class="flex-1 min-w-0">
           {# Breadcrumb line #}
           <div class="flex items-center gap-2 mb-1.5 flex-wrap">
-            <a href="{{ url_for('measure.task_list', recipe_id=task.version_id or task.recipe_id or 0) }}"
+            <a href="{{ url_for('measure.task_list', recipe_id=task.recipe_id or 0) }}"
                class="text-xs text-[var(--text-muted)] hover:text-primary transition-colors inline-flex items-center gap-1">
               <svg class="w-3.5 h-3.5" fill="none" stroke="currentColor" stroke-width="2" viewBox="0 0 24 24">
                 <path stroke-linecap="round" stroke-linejoin="round" d="M10 19l-7-7m0 0l7-7m-7 7h18"/>
@@ -410,7 +410,7 @@
       <div class="flex items-center gap-4">
 
         {# Left: Back button #}
-        <a href="{{ url_for('measure.task_list', recipe_id=task.version_id or task.recipe_id or 0) }}"
+        <a href="{{ url_for('measure.task_list', recipe_id=task.recipe_id or 0) }}"
            class="btn btn-secondary text-xs shrink-0 gap-1.5">
           <svg class="w-3.5 h-3.5" fill="none" stroke="currentColor" stroke-width="2" viewBox="0 0 24 24">
             <path stroke-linecap="round" stroke-linejoin="round" d="M10 19l-7-7m0 0l7-7m-7 7h18"/>
@@ -736,7 +736,7 @@ function taskExecute() {
 
     // ---- Go to summary ----
     goToSummary() {
-      const recipeId = this.task.version_id || this.task.recipe_id || 0;
+      const recipeId = this.task.recipe_id || 0;
       window.location.href = '{{ url_for("measure.task_complete", recipe_id=0) }}'.replace('/0', '/' + recipeId) +
         '?version_id=' + encodeURIComponent(this.task.version_id || '');
     },