build: modernize repo-lens skeleton and cross-platform configuration

Replace CPM with FetchContent and update GoogleTest to v1.18.0.
Add compiler toolchains and Debug, Release, and sanitizer presets.
Require CMake 4.0, use target properties for compiler settings,
and enable compilation database export.

Fix skeleton compilation errors and adopt trailing return types,
nodiscard execute methods, and noexcept signatures. Update CI
and project documentation without implementing any TODOs.

Validated Windows builds and tests in all three configurations.

.github/workflows/ci.yml

@@ -6,70 +6,55 @@ on:
   pull_request:
     branches: [ "main" ]
 
-env:
-  CLANG_TIDY_VERSION: "13.0.0"
-
 jobs:
   build:
-    runs-on: ${{matrix.os}}
+    runs-on: ${{ matrix.platform.os }}
     strategy: 
       fail-fast: false
       matrix:
-        os: [windows-latest, ubuntu-latest, macos-latest]
-        build_configuration: [Debug, Release]
-        compiler: [llvm, gcc]
-
-        exclude:
-          - os: windows-latest
-
-        include:
-          - os: 'windows-latest'
-            compiler: llvm
-            build_configuration: Debug
-
-          - os: 'windows-latest'
-            compiler: llvm
-            build_configuration: Release
-
-          - os: 'windows-latest'
-            compiler: gcc
-            build_configuration: Debug
-
-          - os: 'windows-latest'
-            compiler: gcc
-            build_configuration: Release
-
-          - os: 'windows-latest'
-            compiler: msvc
-            build_configuration: Debug
-
-          - os: 'windows-latest'
-            compiler: msvc
-            build_configuration: Release
-
-          - os: 'ubuntu-latest'
-            triplet: x64-linux
-
-          - os: 'macos-latest'
-            triplet: x64-osx
+        build_configuration: [debug, release, sanitizers]
+        platform:
+          - { os: ubuntu-latest, compiler: gcc }
+          - { os: ubuntu-latest, compiler: clang }
+          - { os: macos-latest, compiler: appleclang }
+          - { os: windows-latest, compiler: msvc }
 
     steps:
     - name: checkout
       uses: actions/checkout@v3
 
+    - name: Set up Python for CMake installation
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.12'
+
+    - name: Install CMake 4.x
+      run: python -m pip install "cmake>=4.0,<5"
+
+    - name: Set up MSVC developer environment
+      if: runner.os == 'Windows'
+      uses: ilammy/msvc-dev-cmd@v1
+
+    - name: Install Ninja on Linux
+      if: runner.os == 'Linux'
+      run: sudo apt-get update && sudo apt-get install -y ninja-build
+
+    - name: Install Ninja on macOS
+      if: runner.os == 'macOS'
+      run: brew list ninja >/dev/null 2>&1 || brew install ninja
+
     - name: cache
       uses: actions/cache@v3
       with:
-        path: "**/CPM_modules"
-        key: ${{ github.workflow }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+        path: build/${{ matrix.platform.compiler }}-${{ matrix.build_configuration }}/_deps
+        key: ${{ runner.os }}-${{ matrix.platform.compiler }}-${{ matrix.build_configuration }}-${{ github.workflow }}-fetchcontent-${{ hashFiles('CMakePresets.json', '**/CMakeLists.txt', '**/*.cmake') }}
 
     - name: Configure CMake
-      run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{matrix.build_configuration}}
+      run: cmake --preset ${{ matrix.platform.compiler }}-${{ matrix.build_configuration }}
 
     - name: Build
-      run: cmake --build ${{github.workspace}}/build --config ${{matrix.build_configuration}}
+      run: cmake --build --preset ${{ matrix.platform.compiler }}-${{ matrix.build_configuration }} --parallel 2
 
     - name: Test
-      working-directory: ${{github.workspace}}/build
-      run: ctest -C ${{matrix.build_configuration}}
+      run: ctest --preset ${{ matrix.platform.compiler }}-${{ matrix.build_configuration }}