feat(scenarios): add test_nextcloud scenario

[t0kubetsu]

Summary

Adds the test_nextcloud dual-lan scenario that deploy-tests the catalog admin-nextcloud box + software.install.nextcloud role. Verified end-to-end: Nextcloud healthy on :8080 with provisioning.

Contents

• scenarios/test_nextcloud/ — lan1 admin-nextcloud-00 (.150.2, vm_id 1002) + lan2 debian-jump-00 (.151.2, vm_id 3002), dual-lan layout.
• Distinct template build IPs (small .140.3 / medium .140.2): the box-octet-derived template IP collided when two boxes share an octet across subnets, which hung the concurrent template boot. The fix lives in the generator (allocate.py, PR feat(r42playbooks): scenario generator — CLI/TUI/API over range42-catalog #77); this scenario carries the corrected output.
• default_vm_ci_dns_ips set (node resolver substituted at workspace creation; 1.1.1.1 is firewalled in-range).
• NTP-and-update-time not enabled (no reachable NTP in egress-filtered ranges; host kvm-clock time is correct).
• _reserved.json registers the scenario (vm_ids 1002, 3002).

Dependencies

Requires the catalog admin-nextcloud box template (range42-catalog PR feat(topology): add admin-nextcloud box template + bootstrap role) and the Debian-based role fixes from dev_ada to be merged into catalog dev first.

Test plan

• Deployed end-to-end via ./test_nextcloud.setup.sh; Nextcloud healthy on 192.168.150.2:8080, /status.php returns {"installed":true,...}.
• Teardown via ./test_nextcloud.delete_all.sh clean.