Debug: Add diagnostic output to CI workflow

Added debugging information to help diagnose CI failures:
- Echo CC environment variable in build and test steps
- Show compiler version after setup
- Add build-essential package for Ubuntu gcc
- Add completion messages for each step

This will help identify whether:
1. The CC environment variable is being set correctly
2. The compilers are installed properly
3. The build is actually completing

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Mark Rosst

.github/workflows/ci.yml

@@ -25,23 +25,32 @@ jobs:
     - name: Setup compiler
       if: runner.os == 'Linux'
       run: |
+        echo "Setting up ${{ matrix.compiler }} on Linux"
+        sudo apt-get update -qq
         if [ "${{ matrix.compiler }}" = "gcc" ]; then
-          sudo apt-get update
-          sudo apt-get install -y gcc
+          sudo apt-get install -y gcc build-essential
         elif [ "${{ matrix.compiler }}" = "clang" ]; then
-          sudo apt-get update
           sudo apt-get install -y clang
         fi
+        ${{ matrix.compiler }} --version
 
     - name: Build
       env:
         CC: ${{ matrix.compiler }}
-      run: make
+      run: |
+        echo "CC is set to: $CC"
+        echo "Running make..."
+        make
+        echo "Build completed"
 
     - name: Run tests
       env:
         CC: ${{ matrix.compiler }}
-      run: make test
+      run: |
+        echo "CC is set to: $CC"
+        echo "Running make test..."
+        make test
+        echo "Tests completed"
 
     - name: Clean
       run: make clean