feat(cluster): support PFN transaction lookup pruning

[Lchangliang]

Summary

• Add a PFN prune reth config template selected when prune_transactionlookup_distance is set in node TOML
• Keep default PFN template behavior unchanged when prune is not configured
• Make local faucet init work on macOS without GNU timeout
• Add postponed annotations import so pfn_chain test collects on Python 3.9

Verification

• python3 gravity_e2e/runner.py --force-init --no-cleanup pfn_chain passed locally: 1 passed, 1 warning in 405.06s
• Render-checked PFN deploy with and without prune_transactionlookup_distance: prune config emits --full --prune.transactionlookup.distance=10064; default config keeps --dev and no prune args