Config: Change server port to 6800 and remove Cargo.lock dependency

Changes:
- Changed server port from 8000 to 6800 (in range 6500-6999 as requested)
- Updated all Docker Compose files (dev and prod)
- Updated all Dockerfiles (removed Cargo.lock dependency)
- Created backend/.dockerignore with Cargo.lock
- Added Cargo.lock to .gitignore (generated by cargo)
- Removed obsolete 'version' attribute from docker-compose files
- Updated all documentation to reflect new port:
  * README.md
  * thoughts/CONFIG.md
  * thoughts/QUICKSTART.md
  * thoughts/verification-report-phase-2.3.md

This fixes Docker build errors where Cargo.lock was not found during COPY operations.
Docker will now generate Cargo.lock during the build process as expected.

backend/docker-compose.yml

@@ -1,4 +1,3 @@
-version: '3.8'
 services:
   backend:
     build:
@@ -6,12 +5,12 @@ services:
       dockerfile: docker/Dockerfile
     container_name: normogen-backend
     ports:
-      - '6000:8000'
+      - '6800:8000'
     environment:
       - RUST_LOG=info
       - SERVER_PORT=8000
       - MONGODB_URI=mongodb://mongodb:27017
-      - MONGODB_DATABASE=normogen
+      - DATABASE_NAME=normogen
     env_file:
       - .env
     depends_on: