feat(ci): update Gitea workflow to include registry login and cache handling adjustments

CLAUDE.md

@@ -138,12 +138,29 @@ Workflow files live in [.gitea/workflows/](.gitea/workflows/). This project uses
 - Secrets are set under Repository → Settings → Secrets → Actions
 - The registry hostname must be derived from `gitea.server_url` (strip the protocol prefix)
 - Triggers use standard `on:` syntax; `tags: '*.*.*'` matches semver pushes without a `v` prefix
+- Do not use `cache-from/cache-to: type=gha` — on this instance's act_runner (v2.0.0), the internal GitHub Actions-cache-compatible proxy is not reachable from job containers (`dial tcp <ip>:<port>: i/o timeout`), a known act_runner docker-executor networking limitation, not a workflow bug. Use `type=registry` instead (push cache blobs to `${{ env.REGISTRY }}/<repo>:buildcache*` — see both `test.yml` and `docker-publish.yml`); it requires a registry login step even for jobs that don't push the final image.
 
 **Current workflows:**
 
 | File                 | Trigger          | Purpose                                                   |
 | -------------------- | ---------------- | --------------------------------------------------------- |
 | `docker-publish.yml` | Push tag `*.*.*` | Build & push multi-arch image to Gitea container registry |
+| `test.yml`           | Push/PR to `main`| Build dev+prod images, run PHPUnit and PHPStan            |
+
+### Release testing with `act`
+
+Before tagging a release (anything that would trigger `docker-publish.yml`), run `test.yml` locally with [`act`](https://github.com/nektos/act) to catch pipeline failures before pushing. `test.yml` uses plain GitHub Actions syntax (no `gitea.*` contexts), so it runs under `act` unmodified.
+
+```bash
+act -j test \
+  -P ubuntu-latest=catthehacker/ubuntu:act-latest \
+  --artifact-server-path /tmp/act-artifacts
+```
+
+- `-P ubuntu-latest=catthehacker/ubuntu:act-latest` — default act runner image lacks a Docker CLI, which the `test` job needs for its nested `docker run` steps
+- `--artifact-server-path` — required for the `upload-artifact`/`download-artifact` steps to work; without it they silently no-op
+
+**If `act` is not installed:** warn the user it's missing and how to install it (`sudo pacman -S act`, or see the repo above) — do not install it yourself or force the check. `docker-publish.yml` is out of scope for `act` (it needs real `gitea.*` context and a live registry secret); don't try to run it locally.
 
 ## Docker