fix: bpo spec initialization for genesis

[barnabasbusa]

Closes: #7778

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]

Unit Test Results

       12 files  ±0    2 436 suites  ±0   45m 6s ⏱️ - 9m 53s
12 678 tests ±0  12 113 ✔️ ±0  565 💤 ±0  0 ❌ ±0 
63 716 runs  ±0  62 988 ✔️ ±0  728 💤 ±0  0 ❌ ±0 

Results for commit 13914f2. ± Comparison against base commit 7a95ab2.