Publish from Gitea: releases, CI and install docs

Gitea implements no Terraform provider registry, so distribution goes
through release archives plus a filesystem mirror. GoReleaser targets
the Gitea release API; the archive names follow HashiCorp's convention
because that is the only shape a filesystem mirror recognises.

No GPG signing: signatures are a registry-protocol requirement and a
filesystem mirror never checks them.

Cross-repo links point at Gitea; Go module paths deliberately do not.

.gitea/workflows/release.yml

@@ -0,0 +1,27 @@
+name: release
+
+on:
+  push:
+    tags: ["v*.*.*"]
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          # GoReleaser builds the changelog from history, so a shallow clone
+          # would produce an empty one.
+          fetch-depth: 0
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.25.x"
+
+      - uses: goreleaser/goreleaser-action@v6
+        with:
+          version: latest
+          args: release --clean
+        env:
+          # Injected by Gitea for every workflow run; no personal token needed.
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}