Synch multigrid rewrite to repository and

broad unicode elimination effort

CLAUDE.md

@@ -106,7 +106,7 @@ Tests and benchmarks that need optional fermion representations are guarded by `
 ### GPU acceleration and the view/memory-manager discipline
 ### Multigrid (`Grid/algorithms/multigrid/`)
 
-Aggregation-based algebraic multigrid for Wilson-type fermions. Key files: `GeneralCoarsenedMatrixMultiRHSV2.h` (the multi-RHS coarse operator, "V2": coarsening by Fourier probing, batched-GEMM apply on a D+1 grid with rhs innermost and unvectorised), `MultiRHSBlockProject.h` (in `deflation/`; the batched-GEMM transfer operators), `PVdagMMultiGrid.h` (three-level non-Hermitian PVdagM chain with dense bottom) and `HDCGMultiGrid.h` (two-level Hermitian HDCG chain) with their `*Params.h` (XML-serialisable parameters), `MrhsMultiGrid.h` (mrhs V-cycle, preconditioner interface, fp64/fp32 seam), `Smoothers.h`, `MultiGridIO.h`, `Aggregates.h` (near-null vector construction), `Geometry.h` (coarse stencils: max-norm-1 boxes of Manhattan radius 1, 2 or 4), `CoarsenedMatrix.h` (the original nearest-neighbour Wilson multigrid). `deprecated/` holds the V1 coarse operators and the Aggregation-based single-RHS ADEF-2, kept only for the pre-2026 drivers. `MultiGrid.h` is the top-level include.
+Aggregation-based algebraic multigrid for Wilson-type fermions. Key files: `GeneralCoarsenedMatrixMultiRHS.h` (`MultiGeneralCoarsenedOperator`, the coarse operator for any number of right-hand sides: coarsening by Fourier probing, batched-GEMM apply on a D+1 grid with rhs innermost and unvectorised), `MultiRHSBlockProject.h` (in `deflation/`; the batched-GEMM transfer operators), `PVdagMMultiGrid.h` (three-level non-Hermitian PVdagM chain with dense bottom) and `HDCGMultiGrid.h` (two-level Hermitian HDCG chain) with their `*Params.h` (XML-serialisable parameters), `MrhsMultiGrid.h` (mrhs V-cycle, preconditioner interface, fp64/fp32 seam), `Smoothers.h`, `MultiGridIO.h`, `Aggregates.h` (near-null vector construction), `Geometry.h` (coarse stencils: max-norm-1 boxes of Manhattan radius 1, 2 or 4), `CoarsenedMatrix.h` (the original nearest-neighbour Wilson multigrid). `deprecated/` holds the superseded coarse operators and the Aggregation-based single-RHS ADEF-2, with class names prefixed `Deprecated` (`DeprecatedGeneralCoarsenedMatrix`, `DeprecatedMultiGeneralCoarsenedMatrix`, `DeprecatedTwoLevelADEF2`); nothing in the library uses them, only older drivers in `examples/` and `tests/debug/`. `MultiGrid.h` is the top-level include.
 
 ### GPU acceleration
 
@@ -174,7 +174,7 @@ Every programme is wrapped in `Grid_init(&argc, &argv)` / `Grid_finalize()` (`Gr
 - Template structure: most classes are templated on `<_FImpl>` (fermion impl) or `<Gimpl>` (gauge impl), which encode the representation and precision. Instantiation is controlled by `--enable-fermion-instantiations`.
 - **Tensor indices are positional, not labelled.** The `Grid/tensors/` arithmetic recurses structurally over the `iScalar`/`iVector`/`iMatrix` nest: each level defines only the {scalar,vector,matrix}² products at its own level, with element types resolved by automatic type deduction, so every colour/spin/lorentz combination composes from ~200 lines (versus the pre-C++11 QDP++/PETE approach of machine-generating every case). An index's meaning derives entirely from its nesting depth counted from the outside; `iScalar` is the identity/broadcast case at every level. Never insert or remove a nesting level casually — the multiplication tables contract by position.
 - **Multigrid coarsening deepens the tensor nest by one level.** A coarse site vector is `iVector<CComplex,nbasis>`, and `innerProduct` on it returns `iScalar<CComplex>` — one level deeper than the fine block scalar. So the block-inner-product scalar type gains one `iScalar` wrapper per MG level (fine: `vTComplex`; level 2: `iScalar<vTComplex>`; see `examples/Example_pvdagm_3level.cc`). When calling `blockInnerProduct`/`blockZAXPY`/`blockOrthogonalise` on coarse fields, the coarse scalar type must match `decltype(innerProduct(siteVector(),siteVector()))` exactly; a wrong depth fails to compile (no viable `operator=` deep in the instantiation chain) rather than mis-contracting.
-- **Grids are borrowed, never owned.** `conformable` is pointer identity, so every object that interoperates must hold the *same* `GridCartesian *`; a class that minted its own grid internally could never conform with anything else. Ownership is therefore not available, and lifetime is managed by scope discipline instead of reference counting: whoever creates a grid retains it beyond every object it handed a reference to. Anything *derived* from a grid inherits this — `~PaddedCell` dereferences its `unpadded_grid`, so a `PaddedCell` cannot even be **destroyed** after its parent grid, only used. Where a consumer must let go early, it offers an explicit hand-back (`MultiGeneralCoarsenedOperatorV2::ReleaseGrid()`) to be called *before* the grid is destroyed.
+- **Grids are borrowed, never owned.** `conformable` is pointer identity, so every object that interoperates must hold the *same* `GridCartesian *`; a class that minted its own grid internally could never conform with anything else. Ownership is therefore not available, and lifetime is managed by scope discipline instead of reference counting: whoever creates a grid retains it beyond every object it handed a reference to. Anything *derived* from a grid inherits this — `~PaddedCell` dereferences its `unpadded_grid`, so a `PaddedCell` cannot even be **destroyed** after its parent grid, only used. Where a consumer must let go early, it offers an explicit hand-back (`MultiGeneralCoarsenedOperator::ReleaseGrid()`) to be called *before* the grid is destroyed.
 
 - The `RealD`/`RealF`/`ComplexD`/`ComplexF` typedefs are used everywhere; avoid raw `double`/`float`.
 - Use `GRID_ASSERT(cond)` (defined in `Grid/GridStd.h`), not bare `assert` — it prints a Grid-formatted message and aborts cleanly under MPI.