v0.26.0: Storage namespace felhom-data/ + test node wipe script

All felhom-managed data on external drives now lives under felhom-data/
subdirectory, cleanly separating controller data from user files.

- backup/paths.go: add FelhomDataDir constant, update 8 path helpers
- stacks/delete.go: add local felhomDataDir constant (circular import
  boundary), update ProtectedHDDPaths + GetStackBackupData
- storage/migrate_drive.go: import backup pkg, fix conflict check, verify,
  rsync excludes (felhom-data/backups/*/restic/), size estimation
- storage/migrate.go: import backup pkg, fix DB dump paths
- web/handlers.go: fix legacy 'storage' path -> backup.AppDataDir()
- storage/format_linux.go: create felhom-data/ instead of storage/
- storage/attach_linux.go: create felhom-data/ instead of storage/
- scripts/felhom-wipe.sh: new multi-level test node wipe script
  (soft/controller/full/nuclear)
- CHANGELOG.md, controller/README.md, scripts/README.md: updated docs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/README.md

@@ -195,3 +195,65 @@ dprune='sudo docker system prune -af'
 
 - **ctop** — Top-like interface for container metrics
 - **lazydocker** — Terminal UI for Docker management
+
+---
+
+## felhom-wipe.sh
+
+**Test node cleanup script with 4 wipe levels.**
+
+Removes felhom-managed data from a node in a controlled, repeatable way. Designed for test/demo nodes to reset state between testing cycles.
+
+### Quick start
+
+```bash
+# Preview what will be removed (dry run — default)
+sudo ./felhom-wipe.sh --level full
+
+# Execute the wipe
+sudo ./felhom-wipe.sh --level full --yes
+```
+
+### Wipe levels
+
+| Level | What it removes |
+|-------|-----------------|
+| `soft` | Controller state files only: `settings.json`, `metrics.db`, `setup-state.json`, `update-state.json`, `session-data.json`, `snapshot-history.json` |
+| `controller` | Soft + all non-infra Docker containers, all Docker volumes (except `portainer_data`), all stack directories (skips protected stacks by default) |
+| `full` | Controller + `felhom-data/` on all storage drives (appdata, backups). Also removes old-style `appdata/` and `backups/` directories for pre-v0.26.0 compatibility. Restarts controller after cleanup. |
+| `nuclear` | Full + `controller.yaml`, all infra containers (controller, traefik, cloudflared, portainer), DR markers (`.felhom-infra-backup/` on all drives), `docker system prune -af --volumes` |
+
+### CLI options
+
+| Option | Description |
+|--------|-------------|
+| `--level <level>` | Required. One of: `soft`, `controller`, `full`, `nuclear` |
+| `--yes` | Execute the wipe. Default is dry-run (preview only). |
+| `--include-protected` | Also remove protected stacks (controller level only). |
+
+### Path auto-detection
+
+- Reads `stacks_dir` and `data_dir` from `/opt/docker/felhom-controller/controller.yaml` if present
+- Reads registered storage paths from `settings.json`
+- Also scans `/mnt/*/` for `felhom-data/` or legacy `appdata/` directories not in the registry
+
+### What is preserved
+
+- OS and system files
+- Infrastructure containers and config (unless `nuclear`)
+- User files: `Dokumentumok/`, `media/`, other non-felhom directories on drives
+- DR markers on drives (unless `nuclear`)
+
+### Safety
+
+- Dry-run by default — shows plan without deleting anything
+- Interactive `YES` confirmation prompt required even with `--yes`
+- Must run as root (`sudo`)
+- Checks Docker is running before proceeding
+- Protected stacks skipped by default (use `--include-protected` to override)
+
+### Redeploy after nuclear wipe
+
+```bash
+curl -fsSL https://gitea.dooplex.hu/admin/deploy-felhom-compose/raw/branch/main/scripts/docker-setup.sh | bash
+```