feat: require exact OMP residency resume

[schickling-assistant]

Problem

OMP resume selection and channel state must identify the same checkpointed native session. Loose selection can resume the wrong session or start fresh.

Goal

Add exact OMP checkpoint, resume, channel-binding, and readiness validation.

Decisions

• Bind agent, runtime, generation, native session, and runtime incarnation.
• Reject fallback selection and unsupported provider versions.
• Validate mandatory resume before any provider child starts.
• Preserve Pi launch classification while extending shared channel plumbing.

Verification

• cargo test --lib omp_session::tests -- --nocapture — 18 passed.
• Hook typecheck fixtures cover the extended OMP channel payload.
• cargo check --workspace passes on the complete stack.

Complexity

OMP needs both provider-state validation and channel evidence. The implementation keeps those two sources bound by one exact generation and incarnation.

Concerns

The admitted OMP version set remains explicit and fail closed.

Friction & bottlenecks

None specific to this layer.

Follow-ups

PR #493 adds the equivalent Claude capability.

References

Depends on PR #491. Part of stack #495.

Posted on behalf of @schickling

field	value
agent_identity	mbp2025.direct.omp.bn5hrz39
session	mbp2025.bn5hrz39
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.1.7
agent_runtime	OMP 18.1.7
tooling_profile	dotfiles@4816a7a