ci: port workflows from .github/ to .forgejo/ (Forgejo Actions)

GitHub torrentclaw org is shadow-banned and the CI lives at git.torrentclaw.com
now. Forgejo Actions is enabled cluster-wide; this moves the workflows into the
runner's natively-watched .forgejo/workflows/ tree and adapts each step so the
existing Forgejo runner ('docker', 'ubuntu-latest' labels) can execute them
without leaning on GitHub-only tooling.

- ci.yml: drop actions/setup-go (use container: golang:1.25), replace
  golangci-lint-action with the upstream install.sh, drop codecov-action
  (third-party, can re-add later with a Forgejo-compatible variant).
- release.yml: drop goreleaser-action (install via curl), wire GITEA_TOKEN +
  the new release.gitea_urls block in .goreleaser.yml so goreleaser publishes
  to Forgejo. Sign step swaps 'gh release upload' for curl against the Forgejo
  releases API (via the in-cluster forgejo:3000 hostname). VirusTotal job
  dropped — depended heavily on 'gh release' wiring; can be reimplemented
  against the Forgejo API later if we re-enable it.
- docker-rebuild.yml: drop docker/login-action + docker/build-push-action,
  use raw 'docker' commands with manually-installed buildx + qemu. Same
  weekly schedule (Mon 04:17 UTC) and same 'latest' refresh behaviour.
- pages.yml: deleted — install.sh / install.ps1 are already served from the
  Hetzner releases volume at torrentclaw.com/install.sh, so the GitHub Pages
  copy was redundant even before the shadow-ban.

.goreleaser.yml: add release.gitea_urls (api=forgejo:3000, download via the
public Forgejo URL) + prerelease:auto. ship.sh uses '--skip=publish' so local
runs aren't affected by the new release block.

.forgejo/workflows/ci.yml

@@ -0,0 +1,105 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Test
+    runs-on: docker
+    container:
+      image: docker.io/library/golang:1.25
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run tests
+        run: go test -v -race -count=1 ./...
+
+  build:
+    name: Build
+    runs-on: docker
+    container:
+      image: docker.io/library/golang:1.25
+    strategy:
+      matrix:
+        goos: [linux, darwin, windows]
+        goarch: [amd64, arm64]
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build
+        env:
+          GOOS: ${{ matrix.goos }}
+          GOARCH: ${{ matrix.goarch }}
+        run: go build -o unarr ./cmd/unarr/
+
+  lint:
+    name: Lint
+    runs-on: docker
+    container:
+      image: docker.io/library/golang:1.25
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install golangci-lint
+        run: |
+          curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/v2.11.4/install.sh \
+            | sh -s -- -b /usr/local/bin v2.11.4
+
+      - name: Run golangci-lint
+        run: golangci-lint run ./...
+
+  coverage:
+    name: Coverage
+    runs-on: docker
+    container:
+      image: docker.io/library/golang:1.25
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install python3
+        run: apt-get update && apt-get install -y --no-install-recommends python3
+
+      - name: Run tests with coverage (all packages)
+        run: |
+          go test -race -coverprofile=coverage.out -covermode=atomic \
+            ./internal/engine/... \
+            ./internal/agent/... \
+            ./internal/cmd/...
+
+      - name: Check coverage threshold (engine + agent)
+        run: |
+          # Threshold applies only to engine and agent — cmd contains interactive UI
+          # commands (config menus, daemon, auth browser) that are not unit-testable.
+          go test -race -coverprofile=coverage-core.out -covermode=atomic \
+            ./internal/engine/... \
+            ./internal/agent/...
+          COVERAGE=$(go tool cover -func=coverage-core.out | grep ^total | awk '{print $3}' | tr -d '%')
+          echo "Coverage on engine+agent: ${COVERAGE}%"
+          python3 -c "
+          coverage = float('${COVERAGE}')
+          threshold = 50.0
+          print(f'Coverage: {coverage:.1f}% (threshold: {threshold}%)')
+          if coverage < threshold:
+              print(f'ERROR: Coverage {coverage:.1f}% is below minimum {threshold}%')
+              exit(1)
+          else:
+              print('OK: Coverage meets minimum threshold')
+          "
+
+  vet:
+    name: Vet
+    runs-on: docker
+    container:
+      image: docker.io/library/golang:1.25
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run go vet
+        run: go vet ./...