fix: wait for LEP-6 proof rows before report

[j-rafique]

Summary

• Adds a bounded SHADOW/SOFT wait before host_reporter submits an epoch report with assigned targets but zero LEP-6 proof rows.
• Adds non-destructive CountResults(epochID) to the LEP-6 result buffer so host_reporter can check for pending rows without draining them.
• Upgrades duplicate-submit-with-proof-row discard logging to WARN and includes proof result class counts.

Why

Testnet storage challenge reports were being submitted at epoch start before LEP-6 dispatch could finish compound proof work.

Late proof rows could then be discarded because the epoch report had already been accepted and the retry hit duplicate-report handling.

This keeps host-report liveness by using a bounded wait window, then still submitting empty proof rows after the window expires.

Validation

• go test ./supernode/host_reporter ./supernode/storage_challenge ./pkg/metrics/lep6 ./supernode/status -count=1 — PASS
• go test ./... -count=1 — PASS
• git diff --check — PASS before commit

Rollout notes

• Canary on the 2 testnet nodes already showing non-zero LEP-6 dispatch counters.
• Observe 3–5 epochs and confirm storage_proof_results rows land on-chain when eligible tickets are hit.
• After canary, enable storage_challenge.lep6.enabled=true across the fleet in batches.

Follow-up

• Expose existing DispatchInternalFailuresTotal and DispatchSignFailuresTotal in status for better operator visibility.