Put pi on PATH and install Claude Code CLI in the image

Two additions:
- ENV PATH prepends /app/node_modules/.bin so `pi` is on PATH inside
  the container (previously `docker exec ... pi ...` failed with
  "command not found").
- `npm install -g @anthropic-ai/claude-code` so the `claude` CLI is
  available — pi-claude-code-provider shells out to it.

Dockerfile

@@ -11,10 +11,15 @@ COPY tsconfig.json tsconfig.build.json ./
 COPY src ./src
 RUN npm run build && npm prune --omit=dev
 
+# Claude Code CLI must be on PATH: pi-claude-code-provider shells out to `claude`.
+RUN npm install -g @anthropic-ai/claude-code
+
 COPY docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh
 RUN chmod +x /usr/local/bin/docker-entrypoint.sh
 
-ENV NODE_ENV=production \
+# Expose `pi` (and any other project-local bin) on PATH so `docker exec` finds it.
+ENV PATH="/app/node_modules/.bin:${PATH}" \
+    NODE_ENV=production \
     WORKSPACE_DIR=/workspace \
     PI_CODING_AGENT_DIR=/pi-agent
 VOLUME ["/workspace", "/pi-agent"]