chore: agentic upgrade

Dockerfile

@@ -1,4 +1,8 @@
 # syntax=docker/dockerfile:1.7-labs
+
+# ---------------------------------------------------------------------------
+# Stage 1: base - system dependencies shared by install and production
+# ---------------------------------------------------------------------------
 FROM oven/bun:1.3.10 AS base
 
 ENV APP_HOME=/app \
@@ -26,12 +30,18 @@ RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
     curl \
     && rm -rf /var/lib/apt/lists/*
 
+# ---------------------------------------------------------------------------
+# Stage 2: deps - install Bun dependencies without project code
+# ---------------------------------------------------------------------------
 FROM base AS deps
 WORKDIR ${APP_HOME}
 COPY package.json bun.lock ./
 RUN NODE_ENV=development bun install --frozen-lockfile
 
-FROM base AS runner
+# ---------------------------------------------------------------------------
+# Stage 3: prod - production target used by compute deployments
+# ---------------------------------------------------------------------------
+FROM base AS prod
 WORKDIR ${APP_HOME}
 
 COPY --from=deps ${APP_HOME}/node_modules ./node_modules
@@ -48,6 +58,9 @@ RUN chown -R bun:bun /app
 
 USER bun
 
-EXPOSE 3001
+EXPOSE 8001
 
 CMD ["bun", "run", "server"]
+
+# Backward-compatible target for the existing local docker-compose.yml.
+FROM prod AS runner