Add Backend Logic for Inserting Attack-Operator Nodes (Forks & Merges)

[KadeMorton]

What it is

Introduce logic to create attack-operator nodes in the backend whenever a fork or merge relationship is established in the flow.

Why it matters

• Required for MITRE-compliant Attack Flow STIX bundles.
• Helps represent logical junctions (AND/OR) in flow execution.

Requirements

• When user creates:
  • Fork → insert attack-operator with type = AND by default
  • Merge → insert attack-operator with incoming edges
• Automatically insert operator nodes if:
  • Multiple parents connect to a single child
• Allow toggle of AND ↔ OR operator type in backend metadata.

Acceptance Criteria

• Operator nodes inserted programmatically as needed.
• Operator type can be toggled (AND/OR).
• Relationships between FlowNodes and operator nodes are maintained.