Replace the Woodpecker pipelines with Actions workflows under `.github/workflows`, matching the conventions the other migrated repositories now use (butterrobot, smtp2shoutrrr, terraria-companion, dharma).
## Workflows
- Jobs run on `ubuntu-latest`, answered with the catthehacker act image — no `ci-base` container.
- Short `uses:` resolves against github.com, so every action carries its real name: `goreleaser/goreleaser-action`, `oven-sh/setup-bun`, `docker/setup-qemu-action`, `docker/setup-buildx-action`.
- The act image carries none of the tooling `ci-base` provided, so each job installs what it calls: `make` everywhere, `build-essential` for the CGO test job, `upx-ucl` for goreleaser's `upx` block, bun for the webapp build, goreleaser itself for `make build`.
- `e2e` gets a Docker-in-Docker service so testcontainers can resolve its mapped ports from inside the job container; Playwright installs with `--with-deps` now that the job has sudo.
## Supporting changes
- `Makefile` drops unused variables and adopts a self-documenting `help` target.
- `.goreleaser.yml` keeps `dockers_v2` for the multi-platform image.
- `Containerfile` moves to Alpine 3.23; nfpm description fixed.
- e2e: shared Docker network so link creation reaches the test web server, `mattn/go-sqlite3` added to the e2e module, `all:dist` embed directive so dot-files ship in the webapp bundle.
Reviewed-on: #1
Felipe M.
291aed39f1