The chain contains op types the explorer has no serializer for (e.g.
ChannelSetKeys, opcode 16), and a single such transaction aborted the
entire backfill. Same approach as #19, adapted to the current tx format:
unrecognized opcodes and proof variants (e.g. the NoProof unit variant)
fall back to an UnknownOp/UnknownSignature pair that preserves the raw
data verbatim. Typed support can be added incrementally; known ops keep
their strict proof-type checks.
Also adds a typed ChannelSetKeys serializer (opcode 16), shaped from a
real op captured on the chain (fixture included) — its DB model already
existed, but with List[bytes] keys, which break the JSON column's utf-8
encoding; changed to HexBytes like every other byte field.
