fix: install claude code CLI in slackbot docker image (#1247)

adds bun and nodejs to the docker image to support the claude agent sdk's
CLI dependency. the SDK requires the @anthropic-ai/claude-code package
which we install globally with bun and add to PATH.

changes:
- copy bun binary from official oven/bun image
- install nodejs 20.x from nodesource
- install @anthropic-ai/claude-code globally via bun
- add /root/.bun/bin to PATH for CLI access

fixes the CLINotFoundError when research_agent.py tries to use ClaudeSDKClient

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

Co-authored-by: Claude <noreply@anthropic.com>

Author: zzstoatzz

examples/slackbot/Dockerfile.slackbot

@@ -1,17 +1,24 @@
 FROM python:3.13-slim
 
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /bin/
+COPY --from=oven/bun:latest /usr/local/bin/bun /usr/local/bin/bun
 
 WORKDIR /app
 
 COPY . /app
 
 RUN apt-get update && \
     apt-get install -y git build-essential curl && \
+    curl -fsSL https://deb.nodesource.com/setup_20.x | bash - && \
+    apt-get install -y nodejs && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/*
 
-RUN uv sync --extra slackbot --no-dev 
+RUN uv sync --extra slackbot --no-dev
+
+RUN bun install -g @anthropic-ai/claude-code
+
+ENV PATH="/root/.bun/bin:${PATH}"
 
 EXPOSE 4200