Update Dockerfiles to copy .env file

- Add .env file copy to all Dockerfile variants (dev, local, prod)
- Ensures environment variables are available in containers
- Part of environment configuration centralization

Dockerfile.local

@@ -14,6 +14,7 @@ RUN echo "server pool.ntp.org iburst" >> /etc/chrony/chrony.conf
 
 # Copy and install Python dependencies
 COPY requirements.txt requirements.txt
+COPY .env .env
 RUN pip install -r requirements.txt
 
 # Copy source code