Restructure release.yml into 4 jobs:
- create-release: shared Gitea release with download table
- build-windows: existing portable ZIP (unchanged)
- build-linux: new tarball with venv + run.sh launcher
- build-docker: push image to Gitea Container Registry
Add build-dist.sh as Linux equivalent of build-dist.ps1.
Docker tags: version + latest (stable only, no latest for alpha/beta/rc).
