fix: use overlay prefix and correct depth for rchash command

[crtahlin]

Summary

Fixes #673

• Truncate overlay to a short even-length hex prefix for the anchor parameter instead of passing the full 64-char overlay address, which caused 400 Bad Request or 500 Internal Server Error from the Bee API
• Use committedDepth from node status as the default depth instead of topology.depth, which is the Kademlia routing depth and unrelated to the redistribution game
• Add --depth option to allow overriding the sampling depth (range 0-32), useful for benchmarking at different depths (e.g. storageRadius vs committedDepth)
• Add integration test for the utility rchash command

Details

The rchash command benchmarks the reserve commitment hash calculation that nodes perform during the Schelling game (storage incentives lottery). The previous implementation had two issues:

1. The full overlay address was passed as the anchor, but the Bee API expects a short hex prefix (enough bytes to cover the depth bits). This caused API errors.
2. topology.depth (Kademlia neighborhood depth) was used instead of committedDepth (the actual depth the node commits to the redistribution contract). These are different values — committedDepth = storageRadius + capacityDoubling.

The --depth flag allows operators to benchmark at specific depths, which is useful since sampling time varies significantly with depth (the node iterates through more reserve chunks at lower depths).

Test plan

• npm run build succeeds
• npm run check passes
• npm run lint:check passes
• New integration test test/command/utility.spec.ts passes
• Full test suite shows no regressions
• Verified against running Bee cluster (local dev and full node)