Feat/agent trigger

[bryanadenhq]

Description

Moves timers and webhooks from the worker runtime to the queen level. Triggers now inject signals into the running queen loop; the queen decides whether to start the worker via run_agent_with_input().

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)

Related Issues

Fixes #6051

Changes Made

• Added _trigger_queue and inject_trigger() to EventLoopNode -- triggers are queued separately from user messages and drained atomically via _drain_trigger_queue()
• SessionManager.load_worker() auto-hoists async_entry_points (timer/webhook) from the worker graph onto the session as available triggers, stripping them from the worker runtime
• New queen tools: set_trigger(), remove_trigger(), list_triggers() -- available in STAGING and RUNNING modes
• Active trigger state persists in SessionState.active_triggers so timers survive server restarts
• 5 new EventBus event types (TRIGGER_AVAILABLE/ACTIVATED/DEACTIVATED/FIRED/REMOVED) for frontend observability
• Frontend: SSE handling for trigger events, countdown-to-next-fire on trigger nodes, task string editor in the node panel
• Queen system prompt updated with trigger handling rules in both STAGING and RUNNING phases

Testing

Describe the tests you ran to verify your changes:

• Unit tests pass (cd core && pytest tests/)
• Lint passes (cd core && ruff check .)
• Manual testing performed

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes