Add delete button for completed jobs in history

- Added delete button next to 'View Result' for completed jobs in history.html
- Button appears only for completed jobs and includes confirmation dialog
- Uses existing /job/{job_id}/delete route which already handles ownership checks
- Maintains consistent styling with other action buttons

Users can now clean up their completed job history by deleting individual jobs they no longer need.

templates/history.html

@@ -248,7 +248,10 @@
                 <div class="job-tokens">{{ job.used_tokens or 0 }}</div>
                 <div class="job-actions">
                     {% if job.status == 'completed' %}
-                    <a href="/job_result/{{ job.id }}" class="view-result-link">View Result</a>
+                    <a href="/job_result/{{ job.id }}" class="view-result-link" style="margin-right: 0.5rem;">View Result</a>
+                    <form method="post" action="/job/{{ job.id }}/delete" style="display: inline;" onsubmit="return confirm('Are you sure you want to delete this completed job?')">
+                        <button type="submit" class="delete-btn" style="background: #dc2626; color: white; border: none; padding: 0.25rem 0.5rem; border-radius: 4px; font-size: 0.8rem; cursor: pointer;">Delete</button>
+                    </form>
                     {% elif job.status == 'processing' %}
                     <form method="post" action="/job/{{ job.id }}/cancel" style="display: inline; margin-right: 0.5rem;" onsubmit="return confirm('Are you sure you want to cancel this running job?')">
                         <button type="submit" class="cancel-btn" style="background: #f59e0b; color: white; border: none; padding: 0.25rem 0.5rem; border-radius: 4px; font-size: 0.8rem; cursor: pointer;">Cancel</button>