feat(docker): update Dockerfile to install Clang 12 and set it as default

.devcontainer/Dockerfile

@@ -7,10 +7,29 @@ ENV DEBIAN_FRONTEND=noninteractive
 RUN apt-get update && apt-get install -y \
     # Build essentials
     build-essential \
-    # Standard clang tools (this will install the default version)
-    clang \
-    clang-format \
-    clang-tidy \
+    # Add LLVM repository for specific Clang versions
+    wget \
+    lsb-release \
+    software-properties-common \
+    gnupg \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install development tools - Ubuntu 22.04 approach
+RUN apt-get update && apt-get install -y \
+    # Build essentials
+    build-essential \
+    # Check what Clang versions are available and install Clang 12 if possible
+    software-properties-common \
+    wget \
+    gnupg \
+    && apt-get update && \
+    # Install available Clang tools (Ubuntu 22.04 has clang-12 available)
+    apt-get install -y \
+    clang-12 \
+    clang++-12 \
+    clang-format-12 \
+    clang-tidy-12 \
+    # clangd and lldb may have different versioning
     clangd \
     lldb \
     # Build tools
@@ -20,7 +39,6 @@ RUN apt-get update && apt-get install -y \
     pkg-config \
     # Version control and utilities
     git \
-    wget \
     curl \
     unzip \
     # Development utilities  
@@ -33,9 +51,17 @@ RUN apt-get update && apt-get install -y \
     # Text processing
     vim \
     nano \
+    # Include What You Use
+    iwyu \
     # Clean up
     && rm -rf /var/lib/apt/lists/*
 
+# Create symbolic links to make clang-12 the default
+RUN update-alternatives --install /usr/bin/clang clang /usr/bin/clang-12 100 \
+    && update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-12 100 \
+    && update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-12 100 \
+    && update-alternatives --install /usr/bin/clang-tidy clang-tidy /usr/bin/clang-tidy-12 100
+
 # Create a non-root user for development
 RUN groupadd --gid 1000 vscode \
     && useradd --uid 1000 --gid vscode --shell /bin/bash --create-home vscode \
@@ -45,9 +71,9 @@ RUN groupadd --gid 1000 vscode \
     && chmod 0440 /etc/sudoers.d/vscode \
     && rm -rf /var/lib/apt/lists/*
 
-# Set clang as the default compiler
-ENV CC=clang
-ENV CXX=clang++
+# Set clang-12 as the default compiler
+ENV CC=clang-12
+ENV CXX=clang++-12
 
 # Set working directory
 WORKDIR /workspace