Refactor Gitea production deployment process to utilize SSH for remote operations

- Updated deployment specification to reflect the new architecture involving servers A, B, and C.
- Revised README to describe the new deployment method using Gitea Runner and SSH.
- Modified `compose.production.yaml` to remove build context and use image tags directly.
- Enhanced deployment documentation to clarify configuration steps and environment variable requirements.
- Introduced `deploy-remote.sh` script for handling remote deployment tasks over SSH.
- Added unit tests for deployment scripts to ensure robustness and error handling.
- Updated `deploy-production.sh` to streamline image pulling and deployment processes.

compose.production.yaml

@@ -13,10 +13,7 @@ x-container-logging: &container-logging
     max-file: "5"
 
 x-backend: &backend
-  image: wq-alpha-production-backend:${DEPLOY_TAG:-local}
-  build:
-    context: .
-    dockerfile: Dockerfile.backend
+  image: ${IMAGE_PREFIX:?Set the Gitea registry/owner/image prefix}-backend:${DEPLOY_TAG:?Set the published release tag}
   environment:
     DATABASE_URL: ${DATABASE_URL:?Set the Gitea DATABASE_URL secret}
     ADMIN_USERNAME: ${ADMIN_USERNAME:-admin}
@@ -32,9 +29,6 @@ x-backend: &backend
     AI_OUTPUT_TOKENS: ${AI_OUTPUT_TOKENS:-4096}
     AI_TIMEOUT: ${AI_TIMEOUT:-180}
     WQ_BASE_URL: ${WQ_BASE_URL:-https://api.worldquantbrain.com}
-  networks:
-    - default
-    - database
 
 services:
   backend:
@@ -67,10 +61,7 @@ services:
       <<: *observability-labels
       observability.service: "web"
     logging: *container-logging
-    image: wq-alpha-production-web:${DEPLOY_TAG:-local}
-    build:
-      context: .
-      dockerfile: Dockerfile.frontend
+    image: ${IMAGE_PREFIX:?Set the Gitea registry/owner/image prefix}-web:${DEPLOY_TAG:?Set the published release tag}
     environment:
       SITE_ADDRESS: http://:80
     ports:
@@ -89,10 +80,6 @@ services:
       start_period: 10s
     restart: unless-stopped
 
-networks:
-  database:
-    external: true
-    name: ${DATABASE_NETWORK:?Set the existing PostgreSQL Docker network}
 volumes:
   caddy_data:
   caddy_config: