chore(onchain_config): assert RSA JWK oracle path is unreachable

[ByteYue]

Summary

• Add panic + error log to the RSA JWK branch in construct_oracle_record_transaction
• This code path is not used in production — all JWK data flows through the UnsupportedJWK (blockchain event / bridge) path via construct_blockchain_batch_transaction
• If this path is ever entered unexpectedly, the node will fail fast with a clear error message instead of silently producing incorrect state

Context

Follow-up to #323. During investigation we confirmed that:

1. The RSA JWK path has never been executed on-chain (zero DataRecorded events for sourceType=1)
2. Bridge data reuses JWK consensus via UnsupportedJWK, which correctly handles nonces from event payloads
3. The RSA JWK path should remain dead code until explicitly needed

Test plan

• Verify node starts and processes blocks normally (RSA JWK path not triggered)
• Verify e2e bridge tests still pass (UnsupportedJWK path unaffected)

🤖 Generated with Claude Code

[Richard1048576]

LGTM