Add local replication reconciliation endpoints

[skgbafa]

Summary

• add host reconciliation endpoints for local replication flows
• support exporting and applying scoped snapshots/ranges
• fix KV delete resolution and stale actor hydration needed by replicated state checks

Current status

This PR is not merge-ready as-is. It was produced as a one-commit delta during the local replication Smithers run, from the submodule revision pinned in tinycloud-dev at the time. That revision was behind main, and this branch is not stacked on the existing replication PR #45 (feat/replication-e2e-bootstrap). GitHub correctly reports it as conflicting with main.

Treat this PR as a small extracted patch/reference for the peer-host-set direction. The next clean step is to rebase or replay the useful reconciliation changes onto the intended replication branch/stack, then rerun the replication harness.

Related

• Existing replication PR: feat: add replication bootstrap and sync auth routes #45
• Workflow/harness PR: https://github.com/TinyCloudLabs/protocol-experiments/pull/1
• Coordination PR: https://github.com/skgbafa/tinycloud-dev/pull/11

Verification

• cargo fmt --check
• cargo build --locked -p tinycloud-node --bin tinycloud