- OpFunctionParameter: the entry block's Block.params round-trip as
OpFunctionParameter (emitted between OpFunction and the entry OpLabel, decoded
back onto the entry block).
- encode computes bound (max <id> + 1) when the caller leaves it 0; a non-zero
bound (e.g. from decode) is preserved, so re-encode is stable.
- Trailing operands an enum value/bit pulls in (MemoryAccess Aligned's alignment,
...) are captured on decode as literals, so enum-parameter instructions
re-encode byte-exact.
Tests: param_function + load_aligned added -> 5 passed.
35fac68c7c