chore: add development tools to devcontainer

Add global npm packages for development:
- @anthropic-ai/claude-code for AI assistance
- @harryisfish/gitt for git workflow management
- @openai/codex for code generation support

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

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

Author: harryisfish

.devcontainer/Dockerfile

@@ -13,7 +13,7 @@ ENV PNPM_HOME /root/.local/share/pnpm \
     && PATH $PNPM_HOME:$PATH
 # 安装 pnpm
 RUN npm config set registry=https://registry.npmmirror.com \
-    && npm i -g pnpm \
+    && npm i -g pnpm @anthropic-ai/claude-code @harryisfish/gitt @openai/codex \
     && pnpm setup \
     && pnpm config set store-dir $PNPM_HOME \
     && pnpm config set registry https://registry.npmmirror.com