refactor: read compose project name from .env instead of hardcoding, rename prod compose file

[itisnotyourenv]

Problem

docker-compose.prod.yml hardcodes the project name as name: "production" (line 2). This is inconsistent with how the other compose files work — docker-compose.yml and docker-compose-test.yml both read container names and other values from .env / .env.example, but the production compose file has a static project name baked in.

Additionally, the production compose file uses a dot-separated naming convention (docker-compose.prod.yml) while the test compose file uses a dash-separated convention (docker-compose-test.yml). This inconsistency makes it harder to discover and reference files.

Current behavior

• docker-compose.prod.yml has name: "production" hardcoded on line 2
• File naming is inconsistent: docker-compose-test.yml (dash) vs docker-compose.prod.yml (dot)

Expected behavior

1. Rename docker-compose.prod.yml → docker-compose-prod.yml to match the existing docker-compose-test.yml naming convention
2. Read project name from .env — add a COMPOSE_PROJECT_NAME variable (or similar) to .env / .env.example and reference it in the compose file instead of hardcoding name: "production"

Files to update

• Rename docker-compose.prod.yml → docker-compose-prod.yml
• Replace name: "production" with name: "${COMPOSE_PROJECT_NAME_PROD}" (or similar env var) in the renamed file
• Add the new env var to .env.example with a sensible default (e.g., COMPOSE_PROJECT_NAME_PROD=production)
• Update .env accordingly
• Update all references in .github/README.md (lines 76, 87, 92)
• Check for any other references to the old filename (justfile, CI, scripts, etc.)

Context

The docker-compose.yml and docker-compose-test.yml files already follow the pattern of reading configuration from .env. This change brings the production compose file in line with that convention, making the setup more configurable and consistent.