- Updated CI workflow to run `go vet` and `go test` for all modules on every push/PR.
- Implemented a `changes` job to rebuild only affected Docker images based on modified paths.
- Introduced caching for Docker builds to speed up subsequent runs by leveraging registry-based cache.
- Modified Dockerfiles for `ai-gateway`, `discord-bot`, `ha-gateway`, and `tts-gateway` to copy `go.mod` and `go.sum` files first, allowing for better caching of dependencies.
- Added `go.sum` file for `tts-gateway` to ensure proper dependency management.
- Ensured that `go mod download` is executed in the correct order to optimize layer caching.
