Refactor ci.nix to use omnix and cachix modules
Instead of manually defining the omnix and cachix jobs in ci.nix, import and use the existing omnix and cachix modules from the flake.
Benefits
- Reduces code duplication: Reuses the same modules exported for users
- More maintainable: Changes to omnix/cachix modules automatically apply to CI
- Cleaner configuration: Simplifies ci.nix from 52 lines to 38 lines
- Automatic stage collection: Stages are automatically gathered from modules and jobs
Changes
The configuration now:
- Imports
omnixandcachixmodules alongsideflake - Enables and configures them declaratively
- Removes manual job definitions (31 lines removed)
The behavior remains identical - the same jobs are generated with the same configuration.