fix: Show scheduled tasks in sidebar after container restart

[moortekweb-art]

Problem

After a container restart, scheduled tasks disappear from the sidebar UI even though they still exist in tmp/scheduler/tasks.json. Users must manually trigger each task to make them visible again.

Root Cause

The poll.py endpoint only returns tasks that have an active AgentContext in memory (AgentContext._contexts). When the container restarts, all AgentContext objects are lost, but tasks persist in the scheduler's JSON file.

Solution

Extend poll.py to also include tasks from TaskScheduler.serialize_all_tasks() that don't have active contexts. This ensures scheduled tasks remain visible in the UI after restarts.

Changes

• Added datetime import
• Added processed_task_uuids set to track which tasks have been processed
• Added loop to include tasks from scheduler that don't have active AgentContexts
• Creates minimal context-like data structure for orphaned tasks

Testing

1. Create a scheduled task
2. Restart the container: docker restart agent-zero
3. Open the UI - task should still be visible in the sidebar

Impact

• No breaking changes
• Backward compatible
• Minimal performance impact (just reads existing scheduler data)