Rename act_runner to runner (#850)

## Consumer-facing breaking changes

- **Go module path**: `gitea.com/gitea/act_runner` → `gitea.com/gitea/runner`. Anything importing `act/...` or `internal/...` packages (notably Gitea itself) must update imports.
- **Binary name**: `act_runner` → `gitea-runner`. Wrapper scripts, systemd units, init scripts, and documentation referencing the binary by `act_runner` will break.
- **Docker image**: `gitea/act_runner` → `gitea/runner` (incl. `*-dind-rootless` variants). Users pulling `gitea/act_runner:nightly` etc. will get stale images. Note: the image name is `gitea/runner`, not `gitea/gitea-runner`.
- **Release artifact paths**: S3 directory `act_runner/{{.Version}}` → `gitea-runner/{{.Version}}`, and artifact filenames change with the new project name. Existing download URLs break.
- **Metrics namespace**: changed from `act_runner` to `gitea_runner` (e.g. `act_runner_jobs_total` → `gitea_runner_jobs_total`); existing monitors/dashboards must be updated.
- **ldflags version path**: `gitea.com/gitea/act_runner/internal/pkg/ver.version` → `gitea.com/gitea/runner/internal/pkg/ver.version`. Affects anyone building with custom ldflags.
- **Kubernetes example resource names**: `act-runner` / `act-runner-vol` → `runner` / `runner-vol`. Users who copied the manifests verbatim will see resource churn on apply.
- **s6 service name**: `scripts/s6/act_runner/` → `scripts/s6/gitea-runner/` (image-internal; only matters for downstream image overrides).

Unchanged: YAML config field names, env vars (`GITEA_*`), CLI flags/subcommands, registration file format.
---------

Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/850
Reviewed-by: Zettat123 <39446+zettat123@noreply.gitea.com>
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Reviewed-by: Nicolas <bircni@icloud.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-committed-by: Lunny Xiao <xiaolunwen@gmail.com>

.gitea/workflows/release-nightly.yml

@@ -69,7 +69,7 @@ jobs:
           password: ${{ secrets.DOCKER_PASSWORD }}
 
       - name: Echo the tag
-        run: echo "${{ env.DOCKER_ORG }}/act_runner:nightly${{ matrix.variant.tag_suffix }}"
+        run: echo "${{ env.DOCKER_ORG }}/runner:nightly${{ matrix.variant.tag_suffix }}"
 
       - name: Build and push
         uses: docker/build-push-action@v6
@@ -82,4 +82,4 @@ jobs:
             linux/arm64
           push: true
           tags: |
-            ${{ env.DOCKER_ORG }}/act_runner:nightly${{ matrix.variant.tag_suffix }}
+            ${{ env.DOCKER_ORG }}/runner:nightly${{ matrix.variant.tag_suffix }}

.gitea/workflows/release-tag.yml

@@ -71,17 +71,12 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
-      - name: Repo Meta
-        id: repo_meta
-        run: |
-          echo REPO_NAME=$(echo ${GITHUB_REPOSITORY} | awk -F"/" '{print $2}') >> $GITHUB_OUTPUT
-
       - name: "Docker meta"
         id: docker_meta
         uses: https://github.com/docker/metadata-action@v5
         with:
           images: |
-            ${{ env.DOCKER_ORG }}/${{ steps.repo_meta.outputs.REPO_NAME }}
+            ${{ env.DOCKER_ORG }}/runner
           tags: |
             type=semver,pattern={{major}}.{{minor}}.{{patch}}
             type=semver,pattern={{major}}.{{minor}}