🔧 configure application environment variables

Sets up environment variables within the docker-compose file,
replacing the use of a .env file. This includes defining
variables for Django secret key, allowed hosts, SMTP settings,
and sender name. This change improves configuration management
and clarifies the necessary environment settings.

docker-compose.yaml

@@ -1,7 +1,6 @@
 ---
 services:
   app:
-    image: git.extrasolar.space/marc/room-booking.git:latest
     build:
         context: .
         dockerfile: Dockerfile
@@ -9,7 +8,14 @@ services:
         - "8000:8000"
     volumes:
         - app-data:/data
-    env_file: .env
+    environment:
+      - DJANGO_SECRET_KEY=A_VERY_SECRETKEY_KEY # adjust this
+      - DJANGO_ALLOWED_HOSTS=www.example.org # adjust this (comma-separated list of allowed hosts)
+      - SMTP_EMAIL=room-booking@example.org # adjust this
+      - SMTP_PASSWORD=YOUR_SMTP_PASSWORD # adjust this
+      - SMTP_SERVER=your.smtp.server # adjust this
+      - SMTP_PORT=587 # adjust this if necessary
+      - SMTP_SENDER_NAME=Room Booking System # adjust this if you want
 
 volumes:
   app-data: