Fix MSVC narrowing warnings (and a latent paso reordering bug)

Four MSVC 2022 warnings on the win-64 conda-forge build, all in escript
code:

* paso/src/Options.h: Options::reordering was declared `bool`, but it stores
  a reordering *strategy code* (PASO_NO_REORDERING == 17,
  PASO_DEFAULT_REORDERING == 30, ...): it is set from
  mapEscriptOption(sb.getReordering()) and passed to MKL_solve(...,
  index_t reordering, ...) which switch()es on it. Storing those codes in a
  bool collapsed them all to 1, silently breaking MKL reordering selection
  on every platform (gcc/clang just didn't warn). Declare it `index_t`,
  which is what every consumer already expects. Fixes MSVC C4305.

* ripley/src/RipleyDomain.cpp and speckley/src/SpeckleyDomain.cpp:
  pair<int,dim_t>(1, m_diracPoints.size()) narrowed the 64-bit size() to
  dim_t. Cast explicitly. Fixes MSVC C4267.

* weipa/src/DataVar.cpp: std::copy from a double source into a float buffer.
  Replace with an explicit static_cast<float> loop (the narrowing is
  intended -- the VTK/SILO export buffer is single precision). Fixes C4244.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Lutz Gross

paso/src/Options.h

@@ -113,7 +113,7 @@ struct PASO_DLL_API Options
     double inner_tolerance;
     bool adapt_inner_tolerance;
     bool verbose;
-    bool reordering;
+    index_t reordering;
     int preconditioner;
     dim_t iter_max;
     dim_t inner_iter_max;

ripley/src/RipleyDomain.cpp

@@ -169,7 +169,7 @@ pair<int,dim_t> RipleyDomain::getDataShape(int fsType) const
         case ReducedFaceElements:
             return pair<int,dim_t>(1, getNumFaceElements());
         case Points:
-            return pair<int,dim_t>(1, m_diracPoints.size());
+            return pair<int,dim_t>(1, static_cast<dim_t>(m_diracPoints.size()));
         default:
             break;
     }

speckley/src/SpeckleyDomain.cpp

@@ -117,7 +117,7 @@ pair<int,dim_t> SpeckleyDomain::getDataShape(int fsType) const
         case ReducedElements:
             return pair<int,dim_t>(1, getNumElements());
         case Points:
-            return pair<int,dim_t>(1, m_diracPoints.size());
+            return pair<int,dim_t>(1, static_cast<dim_t>(m_diracPoints.size()));
         default:
             break;
     }

weipa/src/DataVar.cpp

@@ -165,14 +165,16 @@ bool DataVar::initFromEscript(escript::Data& escriptData, const_DomainChunk_ptr
             const escript::DataTypes::real_t* values =
                 escriptData.getDataRO();
             for (int pointNo=0; pointNo<numSamples*ptsPerSample; pointNo++) {
-                copy(values, values+dimSize, destPtr);
+                for (size_t i=0; i<dimSize; i++)
+                    destPtr[i] = static_cast<float>(values[i]);
                 destPtr += dimSize;
             }
         } else {
             for (int sampleNo=0; sampleNo<numSamples; sampleNo++) {
                 const escript::DataTypes::real_t* values =
                     escriptData.getSampleDataRO(sampleNo);
-                copy(values, values+dataSize, destPtr);
+                for (size_t i=0; i<dataSize; i++)
+                    destPtr[i] = static_cast<float>(values[i]);
                 destPtr += dataSize;
             }
         }