Refactor Docker setup and add mock data support

- Updated .dockerignore and .gitignore for better file management.
- Introduced .env.example for environment variable configuration.
- Added docker-compose.dev.yml for development with mock data and live reload.
- Enhanced Dockerfile to include necessary dependencies and entrypoint script.
- Created mock_data.py to provide sample data for testing without OpenStack/Prometheus.
- Added unit tests for template filters in dashboard.
- Cleaned up various files for consistency and improved readability.

docker-compose.yml

@@ -1,8 +1,24 @@
-services:
-  watcher-visio:
-    build: .
-    ports:
-      - "8000:8000"
-    volumes:
-      - ./:/app
-    restart: unless-stopped
+# Base compose: production-like run.
+# For development with mock data and live reload use:
+#   docker compose -f docker-compose.yml -f docker-compose.dev.yml up --build
+
+services:
+  watcher-visio:
+    image: watcher-visio:latest
+    build:
+      context: .
+      dockerfile: Dockerfile
+    container_name: watcher-visio
+    ports:
+      - "8000:8000"
+    environment:
+      - PYTHONUNBUFFERED=1
+      # Override via environment or env_file (e.g. env_file: .env):
+      # PROMETHEUS_URL, OPENSTACK_CLOUD, OPENSTACK_REGION_NAME, SECRET_KEY
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://127.0.0.1:8000/"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 15s
+    restart: unless-stopped