refactor(backend): revert selective COPY, keep cleanup approach

Address review feedback: keep COPY --from=builder /app /app to avoid
maintenance burden of selective copies. The builder cleanup step still
removes __pycache__, test dirs, pip/poetry caches for size reduction.

Added clarifying comment about --only main referencing the development
docs (dev deps are installed locally, not in production images).

autogpt_platform/backend/Dockerfile

@@ -37,13 +37,15 @@ ENV POETRY_VIRTUALENVS_CREATE=true
 ENV POETRY_VIRTUALENVS_IN_PROJECT=true
 ENV PATH=/opt/poetry/bin:$PATH
 
-RUN pip3 install poetry --break-system-packages
+RUN pip3 install --no-cache-dir poetry --break-system-packages
 
 # Copy and install dependencies
 COPY autogpt_platform/autogpt_libs /app/autogpt_platform/autogpt_libs
 COPY autogpt_platform/backend/poetry.lock autogpt_platform/backend/pyproject.toml /app/autogpt_platform/backend/
 WORKDIR /app/autogpt_platform/backend
-RUN poetry install --no-ansi --no-root
+# Production image only needs runtime deps; dev deps (pytest, black, ruff, etc.)
+# are installed locally via `poetry install --with dev` per the development docs
+RUN poetry install --no-ansi --no-root --only main
 
 # Generate Prisma client
 COPY autogpt_platform/backend/schema.prisma ./
@@ -51,6 +53,15 @@ COPY autogpt_platform/backend/backend/data/partial_types.py ./backend/data/parti
 COPY autogpt_platform/backend/gen_prisma_types_stub.py ./
 RUN poetry run prisma generate && poetry run gen-prisma-stub
 
+# Clean up build artifacts and caches to reduce layer size
+# Note: setuptools is kept as it's a direct dependency (used by aioclamd via pkg_resources)
+RUN find /app -type d -name __pycache__ -exec rm -rf {} + 2>/dev/null || true; \
+    find /app -type d -name tests -exec rm -rf {} + 2>/dev/null || true; \
+    find /app -type d -name test -exec rm -rf {} + 2>/dev/null || true; \
+    rm -rf /app/autogpt_platform/backend/.venv/lib/python*/site-packages/pip* \
+           /root/.cache/pip \
+           /root/.cache/pypoetry
+
 FROM debian:13-slim AS server_dependencies
 
 WORKDIR /app
@@ -68,7 +79,7 @@ RUN apt-get update && apt-get install -y \
     python3-pip \
     && rm -rf /var/lib/apt/lists/*
 
-# Copy only necessary files from builder
+# Copy built artifacts from builder (cleaned of caches, __pycache__, and test dirs)
 COPY --from=builder /app /app
 COPY --from=builder /usr/local/lib/python3* /usr/local/lib/python3*
 COPY --from=builder /usr/local/bin/poetry /usr/local/bin/poetry
@@ -81,9 +92,7 @@ COPY --from=builder /root/.cache/prisma-python/binaries /root/.cache/prisma-pyth
 
 ENV PATH="/app/autogpt_platform/backend/.venv/bin:$PATH"
 
-RUN mkdir -p /app/autogpt_platform/autogpt_libs
-RUN mkdir -p /app/autogpt_platform/backend
-
+# Copy fresh source from context (overwrites builder's copy with latest source)
 COPY autogpt_platform/autogpt_libs /app/autogpt_platform/autogpt_libs
 
 COPY autogpt_platform/backend/poetry.lock autogpt_platform/backend/pyproject.toml /app/autogpt_platform/backend/