Point deployment configs at current git host, strip secrets from docs

Repo moved from git.firebugit.com to git.darksingularity.org; the old
host is gone, which would break both docker-compose's git build
contexts and the Portainer stack setup instructions. Also removes
production secret values (SECRET_KEY, DB passwords, SMTP password)
that were committed in plaintext in the deployment guide.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker-compose.yml

@@ -46,7 +46,7 @@ services:
   # =================================================================
   web:
     build:
-      context: https://git.firebugit.com/Firebug_IT/KeepItGoingServer.git#main
+      context: https://git.darksingularity.org/DarkSingularity/KeepItGoingServer.git#main
       dockerfile: Dockerfile
     container_name: keepitgoing-web
     restart: unless-stopped
@@ -104,7 +104,7 @@ services:
   # =================================================================
   celery-worker:
     build:
-      context: https://git.firebugit.com/Firebug_IT/KeepItGoingServer.git#main
+      context: https://git.darksingularity.org/DarkSingularity/KeepItGoingServer.git#main
       dockerfile: Dockerfile
     container_name: keepitgoing-celery-worker
     restart: unless-stopped
@@ -140,7 +140,7 @@ services:
   # =================================================================
   celery-beat:
     build:
-      context: https://git.firebugit.com/Firebug_IT/KeepItGoingServer.git#main
+      context: https://git.darksingularity.org/DarkSingularity/KeepItGoingServer.git#main
       dockerfile: Dockerfile
     container_name: keepitgoing-celery-beat
     restart: unless-stopped