Turned on the act_runner Actions cache instead of leaving it disabled.
The standalone `cache-server` process was already being launched
unconditionally by zz-act_runner.sh but had no `external_secret`, so it
was refusing to start (the binary requires a non-empty secret even
though its own `cache.enabled` field is unused). Wired a shared,
randomly generated secret through the existing REPLACE_* templating
pattern so the "gitea" runner, the cache-server, and the extra
runner-N daemons spawned by start-runners all share one cache backend.
- rootfs/tmp/etc/act_runner/default_config.yaml: cache.enabled: true;
added external_server (pointed at the local cache-server) and
external_secret placeholders
- rootfs/tmp/etc/act_runner/cache_server.yaml: cache.enabled: true;
added external_secret placeholder (required for the binary to start)
- rootfs/usr/local/etc/docker/init.d/zz-act_runner.sh: added
__gen_cache_secret() (mirrors __gen_auth_token's persisted-token
pattern, stored at $CONF_DIR/tokens/cache_secret); substitutes
REPLACE_RUNNER_CACHE_SECRET into both the runner config and the
cache-server config; exports RUNNER_CACHE_HOST/PORT/SECRET for
start-runners; bumped version stamp
- rootfs/usr/local/bin/start-runners: generates a shared
runners-cache.yaml from the exported cache env vars and passes
--config to both `act_runner register` and `act_runner daemon` for
every runner-N instance, so they use the same external cache server
instead of an unshared per-process local cache
- TODO.AI.md: logged pre-existing script-lint findings (missing `--`
before grep queries throughout zz-act_runner.sh, a UUOC in
start-runners, an unpinned/stale docker.yaml CI workflow, and
forbidden OCI labels in the Dockerfile) surfaced incidentally by the
lint pass for this change but out of scope for it
