feat(contracts): declare expected security platform types on expectations #313

Add an optional expectation_expected_security_platform_types field (and a SecurityPlatformType enum: EDR, XDR, SIEM, SOAR, NDR, ISPM, LLM_FIREWALL, AI_GATEWAY) to the contract Expectation dataclass.

Context: on the OpenAEV platform, technical expectations (DETECTION/PREVENTION/VULNERABILITY) are today pre-seeded with a pending result for every connected security platform, so the target-results view lists all of them. By letting a contract declare which security platform TYPES are expected to fulfil an expectation, the platform can focus detection/prevention on the relevant platforms only. An empty list preserves the current behaviour (any platform); it is typically empty for MANUAL expectations.

This is the blocking library change for the platform + injectors rework.