[Subtask]: Preserve current MatrixOne numeric semantics in Sirius Substrait offload

## Parent Issue

Parent issue: #28966. Related predecessor compatibility coverage: #26159.

## Detail of Subtask

Independently close current MatrixOne numeric/type compatibility gaps in Sirius
Substrait offload. MO can produce Decimal256 intermediates; the current bridge
accepts decimal precision up to 38. Inventory the exact current-main canonical
TPC-H plan failures before selecting a fix; this issue is not a claim that every
query fails or that wide decimals are the only remaining incompatibility.

The embedded-runtime migration may proceed without this work, but all 22 SF1
and SF10 queries must actually execute through Sirius (both MO-reader and
direct-TAE input) before Flight is retired. This is a hard release blocker for
#28966, not a reason to weaken eligibility or count CPU fallback as success.

## Describe implementation you've considered

1. Capture current MO canonical plans, bound overloads, logical/result metadata,
and the exact unsupported types/operators in Q1-Q22.
2. Design value- and metadata-preserving numeric lowering/execution across MO's
exporter, Sirius planning, GPU operators, and result reconstruction.
3. Define exact scale, rounding, overflow, division and NULL behavior before
implementation. Keep transport/embedding work out of this issue.
4. Reuse counterexamples from #26159 and the existing exporter/decimal suites;
verify current-main changes rather than assuming historical benchmark plans.

No SQL rewrites to sidestep the problem, decimal-to-float coercion, unchecked
narrowing, relaxed result comparison, or silent native fallback are acceptable.
Normal agreed floating-point comparison tolerance does not waive exact decimal
semantics. PR #28941 has a separate SUBSTRING metadata admission adjustment;
do not duplicate it or treat it as wide-decimal support.

## Additional information

- [ ] Current-main plan/type failure inventory
- [ ] Separate approved numeric design and concrete PR breakdown
- [ ] Exact positive, boundary, overflow/division, NULL and metadata tests
- [ ] Real GPU execution and native-MO equality for all 22 SF1/SF10 queries
- [ ] Matching embedded MO-reader and direct-TAE results with GPU streams=2

The numeric PR count is deliberately separate from #28966's ten migration PRs.
No numeric implementation is included in the migration foundation work.