chore(ci): tag-triggered release workflow and helpers

Add .gitea/workflows/release.yml: on v* tag push (or manual
dispatch) build the Docker image and push
git.linuxhg.com/games-database/games-api:<tag> plus :latest,
then create/update the Gitea Release from the annotated tag
message. Main-branch pushes do nothing so WIP never ships.

Add cliff.toml (conventional-commit grouping for release
notes), Makefile release target (cliff notes into annotated
tag, then push), and ./release wrapper (accepts 1.0 or
v1.0). Release flow: ./release v1.0, matching bookhoard.

Requires a REGISTRY_TOKEN repo Actions secret (PAT with
write:package and write:repository); Gitea's auto token
lacks package scope.

Makefile

@@ -0,0 +1,33 @@
+.PHONY: help release
+
+# Default target
+help:
+	@echo "Available targets:"
+	@echo ""
+	@echo "Release:"
+	@echo "  ./release v0.1.0            - Tag, push, and release (notes auto-generated from commits)"
+	@echo "  make release VERSION=v0.1.0 - Same, explicit make form"
+
+# Create an annotated version tag carrying auto-generated release notes (git-cliff)
+# and push it. The tag push triggers .gitea/workflows/release.yml, which builds the
+# image and publishes a Gitea Release whose body is this tag's message. Notes come
+# entirely from Conventional Commits — no hand-written message required.
+#
+# git-cliff's --latest needs the tag to exist to scope the notes, so we create a
+# throwaway lightweight tag, generate the notes, replace it with an annotated tag,
+# then push. --cleanup=verbatim keeps the markdown "###" group headers (git's
+# default cleanup would strip lines starting with "#").
+#
+# Requires git-cliff: https://git-cliff.org/install
+# Usage: make release VERSION=v0.1.0
+release:
+	@test -n "$(VERSION)" || { echo "Usage: make release VERSION=v0.1.0"; exit 1; }
+	@command -v git-cliff >/dev/null 2>&1 || { echo "git-cliff not found — install: https://git-cliff.org/install"; exit 1; }
+	@if git rev-parse "$(VERSION)" >/dev/null 2>&1; then echo "Tag $(VERSION) already exists locally — delete it first: git tag -d $(VERSION)"; exit 1; fi
+	@echo "Generating release notes for $(VERSION)..."
+	@git tag "$(VERSION)" HEAD && \
+		(git cliff --latest --config cliff.toml > .release-notes.tmp && git tag -d "$(VERSION)" >/dev/null) || \
+		{ git tag -d "$(VERSION)" >/dev/null 2>&1; rm -f .release-notes.tmp; echo "git-cliff failed"; exit 1; }
+	@git tag -a --cleanup=verbatim -F .release-notes.tmp "$(VERSION)" HEAD && rm -f .release-notes.tmp
+	@git push origin "$(VERSION)"
+	@echo "Pushed $(VERSION) — Gitea Actions will build the image and publish the Release."