Introduce a GitHub Actions workflow for the `main` branch that builds and pushes a Docker image to GitHub Container Registry. Includes concurrency control, permissions, Docker Buildx setup, and caching configuration.
Remove the private apps/server/src/ee git submodule (github.com/docmost/ee)
and the now-empty .gitmodules so that `git clone --recurse-submodules` and CI
checkout no longer fail with 404. The server loads EE only via guarded runtime
require(), so the build succeeds without it (community edition).
Rewrite .github/workflows/release.yml for the fork:
- drop the GitHub App token step and `submodules: recursive` checkout
- publish to GHCR (ghcr.io/vvzvlad/gitmost) via the built-in GITHUB_TOKEN
instead of Docker Hub (docmost/docmost) — no extra secrets required
- add `packages: write` permission and an IMAGE env var
- log in as github.repository_owner; rename release tarballs to gitmost-*
Repoint the Dockerfile image source label to the fork.
