[user1303836]

Summary

• Make Solana gRPC conversion fail when a Yellowstone transaction update lacks the transaction or message payload.
• Avoid fabricating raw metadata with an empty account-key list for malformed transaction updates.
• Add regression coverage for missing transaction and missing message conversion errors.

Validation

• cargo fmt --all --check
• git diff --check
• cargo test -p spectraplex-adapters solana_grpc::tests::test_convert_grpc
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace
• cargo build --release --workspace