chore(mesh): remove circular plate mesh generator

Delete the polar fan mesher that was not wired into `JuliaFEM.jl` includes.

- Drop `src/mesh/circular.jl` (`create_circular_plate_mesh`).

src/mesh/circular.jl

@@ -1,91 +0,0 @@
-# This file is a part of JuliaFEM.
-# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
-
-"""
-    create_circular_plate_mesh(::Type{Tri3};
-                               radius=1.0,
-                               nr=4,
-                               nθ=24) -> Mesh{Tri3}
-
-Generate a polar triangular mesh for a circular mid-surface.
-
-The mesh consists of concentric rings with constant angular resolution.
-The innermost ring is connected to the center node, producing a
-fan-like topology that is well-suited for Kirchhoff plate elements such
-as DKT.
-
-# Keyword Arguments
-- `radius`: Plate radius (default `1.0`).
-- `nr`: Number of radial divisions (minimum 1).
-- `nθ`: Number of angular sectors per ring (minimum 3).
-
-# Node Sets
-- `:all` - All nodes.
-- `:center` - The plate center (single node).
-- `:outer` - Nodes on the outer rim (r = radius).
-
-# Element Sets
-- `:all` - All Tri3 elements.
-
-# Example
-```julia
-mesh = create_circular_plate_mesh(Tri3; radius=0.5, nr=5, nθ=48)
-```
-"""
-function create_circular_plate_mesh(::Type{Tri3};
-    radius::Float64=1.0,
-    nr::Int=4,
-    nθ::Int=24)
-
-    @assert radius > 0 "radius must be positive"
-    @assert nr ≥ 1 "nr (radial divisions) must be ≥ 1"
-    @assert nθ ≥ 3 "nθ (angular divisions) must be ≥ 3"
-
-    nodes = Vec{3,Float64}[]
-    push!(nodes, Vec(0.0, 0.0, 0.0))  # center node
-
-    rings = Vector{Vector{Int}}(undef, nr)
-    for ir in 1:nr
-        ring = Vector{Int}(undef, nθ)
-        r = radius * ir / nr
-        for it in 1:nθ
-            θ = 2π * (it - 1) / nθ
-            push!(nodes, Vec(r * cos(θ), r * sin(θ), 0.0))
-            ring[it] = length(nodes)
-        end
-        rings[ir] = ring
-    end
-
-    connectivity = NTuple{3,UInt32}[]
-    if nr ≥ 1
-        first_ring = rings[1]
-        for k in 1:nθ
-            k_next = k == nθ ? 1 : k + 1
-            push!(connectivity,
-                (UInt32(1), UInt32(first_ring[k]), UInt32(first_ring[k_next])))
-        end
-    end
-
-    for ir in 2:nr
-        inner = rings[ir-1]
-        outer = rings[ir]
-        for k in 1:nθ
-            k_next = k == nθ ? 1 : k + 1
-            push!(connectivity,
-                (UInt32(inner[k]), UInt32(outer[k]), UInt32(inner[k_next])))
-            push!(connectivity,
-                (UInt32(outer[k]), UInt32(outer[k_next]), UInt32(inner[k_next])))
-        end
-    end
-
-    element_sets = Dict{Symbol,Set{UInt32}}(
-        :all => Set(UInt32(1):UInt32(length(connectivity)))
-    )
-
-    node_sets = Dict{Symbol,Set{UInt32}}()
-    node_sets[:all] = Set(UInt32(1):UInt32(length(nodes)))
-    node_sets[:center] = Set([UInt32(1)])
-    node_sets[:outer] = nr == 0 ? Set([UInt32(1)]) : Set(UInt32.(rings[end]))
-
-    return Mesh{Tri3}(nodes, connectivity, element_sets, node_sets)
-end