ui(measure): drop N/M prefix on task title, fix hidden directive

- Remove the "1/2"/"2/2" prefix before the task title; the number circle
  already shows the index.
- The directive showed only "…": line-clamp-1 + whitespace-pre-wrap clamped a
  leading blank line to just the ellipsis. Use line-clamp-2 without pre-wrap so
  the description is actually visible.

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

src/frontend/flask_app/templates/measure/task_list.html

@@ -153,13 +153,12 @@
           <div class="flex-1 min-w-0">
             <!-- Task Title -->
             <h3 class="text-base font-semibold text-[var(--text-primary)] leading-tight truncate">
-              <span class="text-xs font-medium text-[var(--text-muted)] mr-1.5">{{ loop.index }}/{{ tasks|length }}</span>
               {{ task.title or task.name or (_('Task') ~ ' ' ~ loop.index) }}
             </h3>
 
             <!-- Directive -->
             {% if task.directive or task.description %}
-            <p class="text-xs text-[var(--text-secondary)] leading-snug mt-0.5 line-clamp-1 whitespace-pre-wrap">
+            <p class="text-xs text-[var(--text-secondary)] leading-snug mt-0.5 line-clamp-2">
               {{ task.directive or task.description }}
             </p>
             {% endif %}