op-stack EL: publish p2p port + keep discovery on for node_sync nodes (49 composes)

Operator decision 2026-10-04 (sebastian): consensus-layer-synced op-stack nodes used to run
with --nodiscover / --disable-discovery and no published p2p port. A 0-peer EL can never
backfill a dropped-gossip gap, so op-node wedges in FCU-SYNCING until L1 derivation
catches up (katana 09-19..26, zircuit, mode). Blocks still arrive only via op-node; EL
peers are for gap-fill. Our own copies now discover each other implicitly.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RzxemENdcZBCxdGrzXiFvS

op/erigon/boba-mainnet-op-erigon-archive-trace.yml

@@ -66,9 +66,10 @@ services:
       - --metrics
       - --metrics.addr=0.0.0.0
       - --metrics.port=6060
-      - --nodiscover
+      - --nat=extip:${IP}
       - --p2p.allowed-ports=31732
       - --p2p.allowed-ports=36732
+      - --port=11732
       - --rollup.sequencerhttp=https://mainnet.boba.network
       - --rpc.gascap=6000000000
       - --rpc.returndata.limit=1500000