fix(install): backups exist on a default install; retention resolves real world dirs (#6)

Three faces of one gap, all on the supported install path:

- Backup/restore answered 503 out of the box: nothing ever rendered the
  archive PVC, so FELIS_BACKUP_PVC was unset. The bundle now renders the
  PVC (Minecraft namespace, RWO 10Gi, cluster default class) and
  'felis manifests' names it by default (--backup-pvc= is the explicit
  no-store shape); bootstrap passes it through so the generated felis.toml
  [archive] local_path and the jobs' mount path come from one variable.
- Retention was unreachable: bootstrap never passed the reaper flags. It
  now forwards FELIS_WORLDS_HOST_PATH/FELIS_ARCHIVE_LOCAL_PATH, so one
  env enables the daily CronJob; unset keeps today's fail-safe (no reaper,
  nothing deleted).
- Even when enabled it could not find a world on a stock install:
  resolveWorldDir now also resolves the exact local-path directory
  <pv-name>_<ns>_<pvc-name> read from the live PVC's volumeName (never a
  glob, so a stale deleted PV's bytes can't be archived in place of the
  current world). Reaper Role gains persistentvolumeclaims:get (weaker
  than the delete it already held).

README (zh/en) stops promising automatic/scheduled backups and states
retention is opt-in. bootstrap_test covers the env->flag contract.

README_EN.md

@@ -17,8 +17,8 @@ Table of Contents
 
 - **Wake on Join**: Servers start automatically when a player connects, and stop when idle — like hibernate for your server.
 - **Web Dashboard**: Monitor server status, online players, and resource usage from your browser, with backup and restore management.
-- **Auto Backup & Restore**: Scheduled world backups with one-click rollback from any backup point.
-- **World Reaper**: Worlds idle for more than 15 days are automatically backed up and removed to free disk space.
+- **Backup & Restore**: One-click world snapshots into the cluster's archive store, with rollback from any backup point — enabled by default (the installer renders the archive PVC and its path).
+- **World Reaper** (opt in): Worlds idle for more than 15 days are automatically backed up and removed to free disk space. Enable it by setting `FELIS_WORLDS_HOST_PATH` at install time (on k3s: `/var/lib/rancher/k3s/storage`); without it, no world is ever deleted.
 - **Multi-core Support**: Compatible with Paper, Fabric, Forge, and NeoForge, federated behind a Velocity proxy.
 - **Modpack Submission**: Players submit custom modpacks; admin approval triggers automatic build and deployment.
 - **Passkey Login**: Passwordless authentication via fingerprint, face recognition, or hardware security keys.