fix: Add curl to Docker, add active flag to worker_tasks

- Install curl in Docker container for Dutchie HTTP requests
- Add 'active' column to worker_tasks (default false) to prevent
  accidental task execution on startup
- Update task-service to only claim tasks where active=true

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/src/tasks/task-service.ts

@@ -170,6 +170,7 @@ class TaskService {
       WHERE id = (
         SELECT id FROM worker_tasks
         WHERE status = 'pending'
+          AND active = true
           AND (scheduled_for IS NULL OR scheduled_for <= NOW())
           -- Exclude stores that already have an active task
           AND (dispensary_id IS NULL OR dispensary_id NOT IN (