Fix Dockerfile: copy source before pip install

The pyproject.toml references the package source, so src/ must be
present when pip resolves metadata.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -8,16 +8,12 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 WORKDIR /app
 
-# Install Python deps
+# Copy everything and install
 COPY pyproject.toml .
-RUN pip install --no-cache-dir .
-
-# Copy source
+COPY src/ src/
 COPY alembic.ini .
 COPY alembic/ alembic/
-COPY src/ src/
 
-# Install the project itself
 RUN pip install --no-cache-dir -e .
 
 # Create cache directories