Change code-server to per-user installation

- Remove system-wide code-server installation from Dockerfile
- Install code-server per-user on first run in entrypoint.sh
- Provides better security and user isolation
- Each user gets their own code-server configuration

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

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

Dockerfile

@@ -95,9 +95,7 @@ RUN echo "TZ=Asia/Seoul" >> /etc/environment && \
     echo "XMODIFIERS=@im=fcitx" >> /etc/environment
 
 
-## code server
-RUN curl -fsSL https://code-server.dev/install.sh | sh
-RUN which code-server && code-server --version
+# code server will be installed per-user in entrypoint.sh
 
 EXPOSE 3389
 ENTRYPOINT /entrypoint.sh