superseed-sepolia: add pectra_blob_schedule_time + fix eip1559DenominatorCanyon

op-node was crashing post-Jovian and the rollup/genesis configs were missing
two fields present in the live sequencer (sepolia.superseed.xyz
optimism_rollupConfig):
- rollup.json: add pectra_blob_schedule_time=1742486400 (L1 Sepolia Pectra)
- genesis.json: eip1559DenominatorCanyon 0 -> 250 (match chain_op_config)

Verified against the live sequencer. Fixes op-node 'unexpected length: 178'
L1-info parse error. karst_time not yet published by the sequencer (Karst
Sepolia ~2026-06-17 16:00 UTC) - to be added once available.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

op/superseed/sepolia/genesis.json

@@ -30,7 +30,7 @@
       "optimism": {
         "eip1559Elasticity": 6,
         "eip1559Denominator": 50,
-        "eip1559DenominatorCanyon": 0
+        "eip1559DenominatorCanyon": 250
       }
     },
     "nonce": "0x0",