fix(devcontainer): Dockerfile build fails when .dockerignore excludes .git/ (#1234)

## Summary

Fixes the Docker build failure at step 30/30:
```
fatal: not a git repository (or any of the parent directories): .git
```

## Root Cause

`.dockerignore` excludes `.git/`, so `COPY . $APP_DIR` never copies the `.git` directory into the image. However, the final `RUN` step unconditionally runs `git clean -xdf`, which requires a git repository to exist.

## Fix

Wrapped `git clean -xdf` and `rm -rf .git` in a conditional that checks for `.git` directory existence first, falling through silently when absent:

```dockerfile
([ -d .git ] && git clean -xdf && rm -rf .git || true)
```

This makes the Dockerfile work correctly whether `.git` is present (e.g., if `.dockerignore` is modified) or absent (current behavior).

## Quality Gates

| Gate | Result |
|------|--------|
| lint | Pass |
| typecheck | Pass (0 errors) |
| pre-commit hooks | Pass |

(Dockerfile-only change — no Python code modified, so unit/integration tests are unaffected.)

Closes #1233

Reviewed-on: #1234
Reviewed-by: Luis Mendes <luis.mendes@cleverthis.com>
Co-authored-by: Brent E. Edwards <brent.edwards@cleverthis.com>
Co-committed-by: Brent E. Edwards <brent.edwards@cleverthis.com>

.devcontainer/Dockerfile

@@ -25,36 +25,36 @@ RUN sudo apt-get update && \
     sudo apt-get upgrade -y --no-install-recommends && \
     sudo apt-get dist-upgrade -y --no-install-recommends && \
     sudo apt-get install -y --no-install-recommends \
-        # Essential build tools
-        build-essential \
-        libportaudio2 \
-        iproute2 \
-        gcc \
-        g++ \
-        make \
-        # Development utilities
-        curl \
-        wget \
-        git \
-        vim \
-        nano \
-        jq \
-        gawk \
-        pandoc \
-        tree \
-        htop \
-        unzip \
-        ca-certificates \
-        # Shell enhancements
-        zsh \
-        # Networking tools
-        net-tools \
-        iputils-ping \
-        # Process management
-        procps \
-        # For MCP servers
-        gnupg \
-        lsb-release && \
+    # Essential build tools
+    build-essential \
+    libportaudio2 \
+    iproute2 \
+    gcc \
+    g++ \
+    make \
+    # Development utilities
+    curl \
+    wget \
+    git \
+    vim \
+    nano \
+    jq \
+    gawk \
+    pandoc \
+    tree \
+    htop \
+    unzip \
+    ca-certificates \
+    # Shell enhancements
+    zsh \
+    # Networking tools
+    net-tools \
+    iputils-ping \
+    # Process management
+    procps \
+    # For MCP servers
+    gnupg \
+    lsb-release && \
     # Install Node.js 20 (required for many MCP servers)
     curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | sudo gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg && \
     echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_20.x nodistro main" | sudo tee /etc/apt/sources.list.d/nodesource.list && \
@@ -80,56 +80,56 @@ RUN sudo npm install -g @anthropic-ai/claude-code
 
 # Install development tools globally
 RUN sudo pip install --no-cache-dir \
-      "ruff>=0.4.0" \
-      "pyright>=1.1.400" \
-      "pre-commit>=3.8.0" \
-      "commitizen>=4.4.0" \
-      "nox>=2025.4.22" \
-      "uv-mcp" \
-      "uv>=0.8.0" \
-      "dev-kit-mcp-server" \
-      "mkdocs>=1.6.1" \
-      "mike>=2.0.0" \
-      "mkdocs-material>=9.6.0" \
-      "mkdocs-behave>=1.0.0" \
-      "mkdocstrings>=0.30.0" \
-      "mkdocstrings-python>=1.18.2" \
-      "pymdown-extensions>=10.16.1" \
-      "psutil>=7.1.0" \
-      "torch>=2.0.0" \
-      "transformers>=4.30.0" \
-      "tokenizers>=0.15.0" \
-      "hypothesis>=6.136.6" \
-      "aiofiles>=24.1.0" \
-      "pyhamcrest>=2.1.0" \
-      "numpy>=2.3.3" \
-      "huggingface-hub>=0.35.1" \
-      "mkdocs-kroki-plugin>=0.9.0" \
-      "torch>=2.0.0" \
-      "transformers>=4.30.0" \
-      "tokenizers>=0.15.0" \
-      "torch-geometric>=2.7.0" \
-      "rdflib>=7.1.4" \
-      "asv>=0.6.5"
+    "ruff>=0.4.0" \
+    "pyright>=1.1.400" \
+    "pre-commit>=3.8.0" \
+    "commitizen>=4.4.0" \
+    "nox>=2025.4.22" \
+    "uv-mcp" \
+    "uv>=0.8.0" \
+    "dev-kit-mcp-server" \
+    "mkdocs>=1.6.1" \
+    "mike>=2.0.0" \
+    "mkdocs-material>=9.6.0" \
+    "mkdocs-behave>=1.0.0" \
+    "mkdocstrings>=0.30.0" \
+    "mkdocstrings-python>=1.18.2" \
+    "pymdown-extensions>=10.16.1" \
+    "psutil>=7.1.0" \
+    "torch>=2.0.0" \
+    "transformers>=4.30.0" \
+    "tokenizers>=0.15.0" \
+    "hypothesis>=6.136.6" \
+    "aiofiles>=24.1.0" \
+    "pyhamcrest>=2.1.0" \
+    "numpy>=2.3.3" \
+    "huggingface-hub>=0.35.1" \
+    "mkdocs-kroki-plugin>=0.9.0" \
+    "torch>=2.0.0" \
+    "transformers>=4.30.0" \
+    "tokenizers>=0.15.0" \
+    "torch-geometric>=2.7.0" \
+    "rdflib>=7.1.4" \
+    "asv>=0.6.5"
 # Install MCP servers globally (npm-based)
 RUN sudo npm install -g \
-      @crunchloop/mcp-devcontainers \
-      kubernetes-mcp-server \
-      @opentofu/opentofu-mcp-server \
-      @modelcontextprotocol/server-filesystem \
-      @modelcontextprotocol/server-memory \
-      @modelcontextprotocol/server-sequential-thinking \
-      @modelcontextprotocol/server-postgres \
-      @treedy/pyright-mcp \
-      mcp-server-docker \
-      @cucumber/language-server && \
+    @crunchloop/mcp-devcontainers \
+    kubernetes-mcp-server \
+    @opentofu/opentofu-mcp-server \
+    @modelcontextprotocol/server-filesystem \
+    @modelcontextprotocol/server-memory \
+    @modelcontextprotocol/server-sequential-thinking \
+    @modelcontextprotocol/server-postgres \
+    @treedy/pyright-mcp \
+    mcp-server-docker \
+    @cucumber/language-server && \
     # Install MCP servers (pip-based: fetch, git, sqlite) + LSP + security tools
     sudo pip install --no-cache-dir \
-      robotframework-lsp \
-      mcp-server-fetch \
-      mcp-server-git \
-      mcp-server-sqlite \
-      semgrep
+    robotframework-lsp \
+    mcp-server-fetch \
+    mcp-server-git \
+    mcp-server-sqlite \
+    semgrep
 
 # Create directories for MCP server configurations and logs
 RUN mkdir -p ~/.config/claude-code \
@@ -215,10 +215,10 @@ RUN sudo pip install python-lsp-server[all]
 
 # Install additional LSP servers
 RUN sudo npm install -g \
-      yaml-language-server \
-      vscode-json-languageserver \
-      dockerfile-language-server-nodejs \
-      bash-language-server
+    yaml-language-server \
+    vscode-json-languageserver \
+    dockerfile-language-server-nodejs \
+    bash-language-server
 
 ENV FORGEJO_URL="https://git.cleverthis.com/"
 COPY .devcontainer/crush.json ${USER_HOME}/.config/crush/crush.json
@@ -231,8 +231,8 @@ WORKDIR $APP_DIR
 RUN sudo chown -R ${USER_UID}:${USER_GID} "$APP_DIR" && \
     cd $APP_DIR && \
     git config --global --add safe.directory /app && \
-    git clean -xdf && \
-    rm -rf .git && \
+    # Clean and remove .git only if it was copied (not excluded by .dockerignore)
+    ([ -d .git ] && git clean -xdf && rm -rf .git || true) && \
     # So git doesn't complain about unusual permissions
     sudo git config --system --add safe.directory ${APP_DIR}