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/build.yml

@@ -0,0 +1,40 @@
+name: build
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch: {}
+
+env:
+  GO_VERSION: "1.25.x"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: ${{ env.GO_VERSION }}
+          cache-dependency-path: go.sum
+
+      - name: Format
+        run: test -z "$(gofmt -l .)" || { gofmt -l .; echo "run gofmt -w ."; exit 1; }
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Build
+        run: go build ./...
+
+      - name: Test
+        run: go test ./... -count=1
+
+      # The bridge in pulumi-dokploy reaches the provider through `shim`, and
+      # `internal/provider` is not importable from outside this module. If that
+      # entry point ever stops compiling on its own, the Pulumi build breaks
+      # somewhere far away from the cause.
+      - name: The shim package still builds standalone
+        run: go build ./shim/