Enhance CMake multi-platform workflow

Updated the CMake multi-platform workflow to include macOS and improve structure.

Author: HaplessIdiot

.github/workflows/cmake-multi-platform.yml

@@ -0,0 +1,34 @@
+name: CMake Multi-Platform Build
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    name: Build (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      # ------------------------------
+      # Install dependencies per platform
+      # ------------------------------
+      - name: Install dependencies (Linux)
+        if: matrix.os == 'ubuntu-latest'
+        run: |
+          sudo apt update
+          sudo apt install -y \
+            clang \
+            ninja-build \
+            pkg-config \
+            libgtk-3-dev \