docs: add CI/release documentation and ignore dist directory

Add `/dist/` to `.gitignore` to exclude locally built distribution
artifacts. Document the Gitea Actions workflow, release tagging, and
branch protection setup in the README.

scripts/ci/test.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+repo_root="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/../.." && pwd -P)"
+cd -- "$repo_root"
+
+go test ./...
+go test -tags gtk ./...
+go vet ./...
+go vet -tags gtk ./...
+
+shellcheck \
+  scripts/download-models.sh \
+  scripts/distrobox/common.sh \
+  scripts/distrobox/build.sh \
+  scripts/distrobox/run.sh \
+  scripts/ci/test.sh \
+  scripts/ci/package-release.sh \
+  scripts/ci/publish-release.sh