Fix build on Mac OS, introduce Mac OS CI workflow

Closes #3312

.github/workflows/macos.yml

@@ -0,0 +1,69 @@
+name: Mac OS build
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - master
+      - fixes
+      - develop
+      - release/*
+    tags:
+      - 'v[0-9]+.*'
+  pull_request:
+    branches:
+      - master
+      - fixes
+      - develop
+      - release/*
+
+env:
+  # Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
+  BUILD_TYPE: Release
+
+jobs:
+  mosquitto:
+    runs-on: macos-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: pin cmake to 3.x series
+        uses: jwlawson/actions-setup-cmake@09fd9b0fb3b239b4b68d9256cd65adf8d6b91da0
+        with:
+          cmake-version: '3.31.6'
+
+      - name: Install Homebrew dependencies
+        run: |
+          brew update
+          brew install \
+            argon2 \
+            cjson \
+            cmake \
+            cunit \
+            docbook-xsl \
+            gcc \
+            libedit \
+            libmicrohttpd \
+            make \
+            openssl \
+            uthash
+
+      - name: Configure CMake
+        run: |
+          EDITLINE_PREFIX=$(brew --prefix libedit)
+          cmake -B ${{github.workspace}}/build64 \
+            -G Ninja \
+            -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} \
+            -DDOCUMENTATION=OFF \
+            -DWITH_WEBSOCKETS=ON \
+            -DWITH_TESTS=OFF \
+            -DCMAKE_INCLUDE_PATH="$EDITLINE_PREFIX/include" \
+            -DCMAKE_LIBRARY_PATH="$EDITLINE_PREFIX/lib" \
+            -DCMAKE_C_FLAGS="-I$EDITLINE_PREFIX/include" \
+            -DCMAKE_EXE_LINKER_FLAGS="-L$EDITLINE_PREFIX/lib" \
+            -DOPENSSL_ROOT_DIR=$(brew --prefix openssl@3)
+      - name: Build
+        run: |
+          cmake --build ${{github.workspace}}/build64 \
+            --config ${{env.BUILD_TYPE}}