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.

cliff.toml

@@ -0,0 +1,37 @@
+# git-cliff configuration — generates the body of each Gitea Release from
+# Conventional Commits accumulated since the previous tag. Used locally by
+# `make release` with --latest so only the current tag's section is emitted
+# (no full history, no header — the Gitea Release title is the tag).
+# Docs: https://git-cliff.org/docs/configuration
+
+[changelog]
+header = ""
+body = """
+{% for group, commits in commits | group_by(attribute="group") %}\
+### {{ group | upper_first }}
+{% for commit in commits %}\
+- {% if commit.scope %}*({{ commit.scope }})* {% endif %}{{ commit.message | upper_first }} ({{ commit.id | truncate(length=7, end="") }})
+{% endfor %}\
+{% endfor %}\
+"""
+trim = true
+footer = ""
+
+[git]
+conventional_commits = true
+filter_unconventional = false
+require_conventional = false
+split_commits = false
+commit_parsers = [
+  { message = "^feat", group = "Features" },
+  { message = "^fix", group = "Bug Fixes" },
+  { message = "^perf", group = "Performance" },
+  { message = "^refactor", group = "Refactor" },
+  { message = "^docs", group = "Documentation" },
+  { message = "^test", group = "Tests" },
+  { message = "^chore|^ci", group = "Miscellaneous Tasks" },
+  { message = ".*", group = "Other" },
+]
+filter_commits = false
+tag_pattern = "v[0-9].*"
+sort_commits = "oldest"