feat: expose deployment build identity

.env.production.example

@@ -8,6 +8,8 @@ POSTGRES_USER=rf4
 POSTGRES_PASSWORD=replace-with-long-random-value
 # URL-encode special characters from POSTGRES_PASSWORD in this URL.
 DATABASE_URL=postgresql+psycopg://rf4:replace-with-url-encoded-password@db:5432/rf4_spotter
+APP_VERSION=0.1.0
+APP_REVISION=replace-with-git-commit-sha
 
 ADMIN_TOKEN=replace-with-at-least-32-random-characters
 RATE_LIMIT_SECRET=replace-with-at-least-32-random-characters