fix: docker-setup fails on Synology because of problem with bun (#1002)

Dockerfile

@@ -25,6 +25,8 @@ RUN pnpm install --frozen-lockfile
 
 COPY . .
 RUN pnpm build
+# Force pnpm for UI build (Bun may fail on ARM/Synology architectures)
+ENV CLAWDBOT_PREFER_PNPM=1
 RUN pnpm ui:install
 RUN pnpm ui:build