Add devcontainer for debugging with latest build tools

Provides a sandboxed Ubuntu 24.04 environment with LLVM 21
(clang, clangd, lld, lldb, libc++), cmake, ninja, and ccache
for building and debugging the decompiler with up-to-date tooling.

While there are only minimal VSCode extensions installed by default, I
automatically install Claude Code and my own dotfiles plus additional tools

.devcontainer/Dockerfile

@@ -0,0 +1,37 @@
+FROM mcr.microsoft.com/devcontainers/base:ubuntu-24.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+ENV LLVM_VERSION=21
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates \
+        gnupg \
+        wget \
+        software-properties-common \
+    && wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | gpg --dearmor -o /usr/share/keyrings/llvm-archive-keyring.gpg \
+    && echo "deb [signed-by=/usr/share/keyrings/llvm-archive-keyring.gpg] http://apt.llvm.org/noble/ llvm-toolchain-noble-${LLVM_VERSION} main" \
+        > /etc/apt/sources.list.d/llvm.list \
+    && apt-get update && apt-get install -y \
+        clang-${LLVM_VERSION} \
+        clangd-${LLVM_VERSION} \
+        lld-${LLVM_VERSION} \
+        llvm-${LLVM_VERSION}-dev \
+        libclang-${LLVM_VERSION}-dev \
+        libc++-${LLVM_VERSION}-dev \
+        libc++abi-${LLVM_VERSION}-dev \
+        lldb-${LLVM_VERSION} \
+        cmake \
+        ninja-build \
+        git \
+        zlib1g-dev \
+        ccache \
+        doxygen \
+        graphviz \
+    && update-alternatives --install /usr/bin/cc cc /usr/bin/clang-${LLVM_VERSION} 100 \
+    && update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++-${LLVM_VERSION} 100 \
+    && update-alternatives --install /usr/bin/clang clang /usr/bin/clang-${LLVM_VERSION} 100 \
+    && update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-${LLVM_VERSION} 100 \
+    && update-alternatives --install /usr/bin/lld lld /usr/bin/lld-${LLVM_VERSION} 100 \
+    && update-alternatives --install /usr/bin/lldb lldb /usr/bin/lldb-${LLVM_VERSION} 100 \
+    && update-alternatives --install /usr/bin/clangd clangd /usr/bin/clangd-${LLVM_VERSION} 100 \
+    && apt-get clean && rm -rf /var/lib/apt/lists/*

.devcontainer/devcontainer.json

@@ -0,0 +1,19 @@
+{
+  "name": "sleigh",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
+  "runArgs": [
+    "--cap-add=SYS_PTRACE",
+    "--security-opt=seccomp=unconfined",
+    "--privileged" 
+  ],
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cmake-tools",
+        "llvm-vs-code-extensions.vscode-clangd",
+      ]
+    }
+  }
+}