fix: bpo spec initialization for genesis

[barnabasbusa]

The code was checking if currentBPO.EPOCH.uint64 != 0.uint64 before adding blob schedule entries.
This incorrectly filtered out epoch 0 (genesis), causing the API to return an empty BLOB_SCHEDULE array when BPO was scheduled for epoch 0. Probably the check was supposed to be for MAX_BLOBS_PER_BLOCK ?

This PR results in nimbus returning for BPO_1 scheduled to epoch 0:

    "BLOB_SCHEDULE": [
      {
        "EPOCH": "0",
        "MAX_BLOBS_PER_BLOCK": "15"
      }
    ],

[github-actions]

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