Implement a Sandboxwich detonation provider with capability and egress gates

[haasonsaas]

Context

Detonation is already behind a provider trait and CAPEv2 is optional, but the corpus needs a typed integration path for the EvalOps sandbox control plane without silently assuming that every provider supplies a hostile-malware boundary.

Proposal

Implement a SandboxwichProvider that advertises capabilities, submits only when policy and egress gates allow it, binds the job to an artifact digest and tenant, polls a bounded operation, and maps results into the existing analysis/finding contract.

Acceptance criteria

• Provider capability metadata distinguishes simulated, container, gVisor/Kata, and VM isolation.
• Sample egress is disabled by default and every submission is audited before bytes leave.
• Timeout, cancellation, provider loss, and incomplete reports produce explicit statuses.
• Integration tests use a fake provider and do not require a live hostile workload.

References

• detonation provider trait
• egress gate and audit-before-submit
• sandbox boundary warning