feat(workers): Add proxy reload, staggered tasks, and bulk proxy import

- Periodic proxy reload: Workers now reload proxies every 60s to pick up changes
- Staggered task scheduling: New API endpoints for creating tasks with delays
- Bulk proxy import: Script supports multiple URL formats including host:port:user:pass
- Proxy URL column: Migration 086 adds proxy_url for non-standard formats

Key changes:
- crawl-rotator.ts: Added reloadIfStale(), isStale(), setReloadInterval()
- task-worker.ts: Calls reloadIfStale() in main loop
- task-service.ts: Added createStaggeredTasks() and createAZStoreTasks()
- tasks.ts: Added POST /batch/staggered and /batch/az-stores endpoints
- import-proxies.ts: New script for bulk proxy import
- CLAUDE.md: Documented staggered task workflow

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

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

backend/src/routes/tasks.ts

@@ -976,6 +976,123 @@ router.post('/migration/full-migrate', async (req: Request, res: Response) => {
   }
 });
 
+// ============================================================
+// STAGGERED BATCH TASK CREATION
+// ============================================================
+
+/**
+ * POST /api/tasks/batch/staggered
+ * Create multiple tasks with staggered start times
+ *
+ * This endpoint prevents resource contention when creating many tasks by
+ * staggering their scheduled_for timestamps. Each task becomes eligible
+ * for claiming only after its scheduled time.
+ *
+ * WORKFLOW:
+ * 1. Tasks created with scheduled_for = NOW() + (index * stagger_seconds)
+ * 2. Worker claims task only when scheduled_for <= NOW()
+ * 3. Worker runs preflight on EVERY task claim
+ * 4. If preflight passes, worker executes task
+ * 5. If preflight fails, task released back to pending for another worker
+ *
+ * Body:
+ * - dispensary_ids: number[] (required) - Array of dispensary IDs
+ * - role: TaskRole (required) - 'product_refresh' | 'product_discovery'
+ * - stagger_seconds: number (default: 15) - Seconds between each task start
+ * - platform: string (default: 'dutchie')
+ * - method: 'curl' | 'http' | null (default: null)
+ */
+router.post('/batch/staggered', async (req: Request, res: Response) => {
+  try {
+    const {
+      dispensary_ids,
+      role,
+      stagger_seconds = 15,
+      platform = 'dutchie',
+      method = null,
+    } = req.body;
+
+    if (!dispensary_ids || !Array.isArray(dispensary_ids) || dispensary_ids.length === 0) {
+      return res.status(400).json({ error: 'dispensary_ids array is required' });
+    }
+
+    if (!role) {
+      return res.status(400).json({ error: 'role is required' });
+    }
+
+    const result = await taskService.createStaggeredTasks(
+      dispensary_ids,
+      role as TaskRole,
+      stagger_seconds,
+      platform,
+      method
+    );
+
+    const totalDuration = (dispensary_ids.length - 1) * stagger_seconds;
+    const estimatedEndTime = new Date(Date.now() + totalDuration * 1000);
+
+    res.status(201).json({
+      success: true,
+      created: result.created,
+      task_ids: result.taskIds,
+      stagger_seconds,
+      total_duration_seconds: totalDuration,
+      estimated_completion: estimatedEndTime.toISOString(),
+      message: `Created ${result.created} staggered ${role} tasks (${stagger_seconds}s apart, ~${Math.ceil(totalDuration / 60)} min total)`,
+    });
+  } catch (error: unknown) {
+    console.error('Error creating staggered tasks:', error);
+    res.status(500).json({ error: 'Failed to create staggered tasks' });
+  }
+});
+
+/**
+ * POST /api/tasks/batch/az-stores
+ * Convenience endpoint to create staggered tasks for Arizona stores
+ *
+ * Body:
+ * - total_tasks: number (default: 24) - Total tasks to create
+ * - stagger_seconds: number (default: 15) - Seconds between each task
+ * - split_roles: boolean (default: true) - Split between product_refresh and product_discovery
+ */
+router.post('/batch/az-stores', async (req: Request, res: Response) => {
+  try {
+    const {
+      total_tasks = 24,
+      stagger_seconds = 15,
+      split_roles = true,
+    } = req.body;
+
+    const result = await taskService.createAZStoreTasks(
+      total_tasks,
+      stagger_seconds,
+      split_roles
+    );
+
+    const totalDuration = (result.total - 1) * stagger_seconds;
+    const estimatedEndTime = new Date(Date.now() + totalDuration * 1000);
+
+    res.status(201).json({
+      success: true,
+      total: result.total,
+      product_refresh: result.product_refresh,
+      product_discovery: result.product_discovery,
+      task_ids: result.taskIds,
+      stagger_seconds,
+      total_duration_seconds: totalDuration,
+      estimated_completion: estimatedEndTime.toISOString(),
+      message: `Created ${result.total} staggered tasks for AZ stores (${result.product_refresh} refresh, ${result.product_discovery} discovery)`,
+    });
+  } catch (error: unknown) {
+    console.error('Error creating AZ store tasks:', error);
+    res.status(500).json({ error: 'Failed to create AZ store tasks' });
+  }
+});
+
+// ============================================================
+// TASK POOL MANAGEMENT
+// ============================================================
+
 /**
  * GET /api/tasks/pool/status
  * Check if task pool is paused