fix: remove redundant Python tool installations from devcontainer

Removes manual pip installation of black, flake8, and isort that was causing 
build failures due to permission errors and PEP 668 restrictions. These tools 
are already provided by the installed VS Code Python extensions and don't need 
to be manually installed via pip.

This reverts to the original working devcontainer approach where development 
tools are handled through VS Code extensions rather than manual package 
installations, avoiding both permission issues and tool duplication.

Fixes devcontainer build failure and maintains the intended development 
environment functionality.

.devcontainer/Dockerfile

@@ -70,16 +70,6 @@ RUN sh -c "$(wget -O- https://github.com/deluan/zsh-in-docker/releases/download/
   -a "export PROMPT_COMMAND='history -a' && export HISTFILE=/commandhistory/.bash_history" \
   -x
 
-# Install Python packages and create symlink
-# Fix for PEP 668 "externally-managed-environment" error in Python 3.11+
-# The --break-system-packages flag is safe to use in this devcontainer environment
-# because we're in an isolated container where system package conflicts won't
-# affect the host system. This allows pip to install packages globally within
-# the container, which is the expected behavior for development environments.
-RUN pip3 install --upgrade pip --break-system-packages && \
-  pip3 install black flake8 isort --break-system-packages && \
-  ln -sf /usr/bin/python3 /usr/local/bin/python
-
 # Install Claude
 RUN npm install -g @anthropic-ai/claude-code