Async nodes

[valerypopoff]

Added a new "Async Node" toggle for nodes. If a node is marked as async, it won't block the processing queue. The graph won't wait for this node to complete before finishing.

Async mode only works for nodes that don't have outgoing connections. Adding outgoing connections will turn the 'Async' toggle off. Node types that DO NOT get the "Async Node" toggle in the editor:

  'graphInput',
  'graphOutput',
  'context',
  'raiseEvent',
  'waitForEvent',
  'passthrough',
  'raceInputs',
  'setGlobal',
  'coalesce',
  'compare',
  'delay',
  'if',
  'ifElse',
  'loopController',
  'loopUntil',
  'match'

Use cases:

• Logs & Notifications — Non-critical HTTP calls where you don’t read the response.
• Background Work Dispatch — Enqueue to queues or trigger webhooks without awaiting completion.
• Data Sinks & Maintenance — Upserts to search/vector indexes or cache warming performed after producing the output.