feat: Integrate FEMBasis into JuliaFEM module (partial)

- Add Tensors and Calculus to Project.toml dependencies
- Add basis includes to src/JuliaFEM.jl (Phase 1 integration)
- Fix FEMBasis. namespace references → use JuliaFEM namespace
- Update create_basis.jl: AbstractBasis (not FEMBasis.AbstractBasis)

Status: Basis files load, but conflict with FEMBase expectations
Next: Need to consolidate FEMBase or work around AbstractElement type constraints

This is expected during consolidation - we're bridging two systems.

src/JuliaFEM.jl

@@ -107,6 +107,8 @@ module JuliaFEM
 
 using SparseArrays, LinearAlgebra, Statistics
 using Reexport, ForwardDiff, LightXML, HDF5, Parameters
+using Tensors  # For basis functions (Vec type)
+import Calculus  # For symbolic differentiation in basis generation
 
 import FEMSparse
 
@@ -115,6 +117,24 @@ import FEMBase: get_unknown_field_name, get_unknown_field_dimension,
                 assemble!, update!, initialize!
 using FEMBase: get_problems
 
+# Consolidate FEMBasis.jl into src/basis/ (Phase 1)
+include("basis/abstract.jl")
+include("basis/subs.jl")
+include("basis/vandermonde.jl")
+include("basis/create_basis.jl")
+include("basis/lagrange_segments.jl")
+include("basis/lagrange_quadrangles.jl")
+include("basis/lagrange_triangles.jl")
+include("basis/lagrange_tetrahedrons.jl")
+include("basis/lagrange_hexahedrons.jl")
+include("basis/lagrange_wedges.jl")
+include("basis/lagrange_pyramids.jl")
+include("basis/nurbs.jl")
+include("basis/nurbs_segment.jl")
+include("basis/nurbs_surface.jl")
+include("basis/nurbs_solid.jl")
+include("basis/math.jl")
+
 using TimerOutputs
 export @timeit, print_timer
 

src/basis/abstract.jl

@@ -12,7 +12,7 @@ import Calculus
 export Vec
 
 # Type alias for coordinate inputs (tuples or Vec)
-const Vecish{N, T} = Union{NTuple{N, T}, Vec{N, T}}
+const Vecish{N,T} = Union{NTuple{N,T},Vec{N,T}}
 
 """
     AbstractBasis{dim}

src/basis/create_basis.jl

@@ -78,7 +78,7 @@ function create_basis(name, description, X::Vector{<:Vecish{D, T}}, basis, dbasi
     end
 
     code = quote
-        struct $name <: FEMBasis.AbstractBasis{$D}
+        struct $name <: AbstractBasis{$D}
         end
 
         Base.@pure function Base.size(::Type{$name})
@@ -94,18 +94,18 @@ function create_basis(name, description, X::Vector{<:Vecish{D, T}}, basis, dbasi
             return $N
         end
 
-        function FEMBasis.get_reference_element_coordinates(::Type{$name})
+        function get_reference_element_coordinates(::Type{$name})
             return $X
         end
 
-        @inline function FEMBasis.eval_basis!(::Type{$name}, N::Vector{<:Number}, xi::Vec)
+        @inline function eval_basis!(::Type{$name}, N::Vector{<:Number}, xi::Vec)
             @assert length(N) == $N
             $unpack
             @inbounds $Q
             return N
         end
 
-        @inline function FEMBasis.eval_dbasis!(::Type{$name}, dN::Vector{<:Vec{$D}}, xi::Vec)
+        @inline function eval_dbasis!(::Type{$name}, dN::Vector{<:Vec{$D}}, xi::Vec)
             @assert length(dN) == $N
             $unpack
             @inbounds $V