fix(render): device-context tag/hostgroup rendering and UI previews

[berlikm]

Summary

Device/VM context for Jinja2 tag & hostgroup rendering, plus UI previews (#121).

Rebased onto 1.0.5 + #115 + #117. Depends on #117. Render-only delta:

https://github.com/berlikm/nbxsync/compare/feature/templaterule-regex...fix/tag-render-device-context

Also covers #102: tag/hostgroup templates get device, site, tenant, role, device_type, and manufacturer aliases. Those keys are filled from the render object (the Device/VM during host sync), not from the assignment row — so a Role-level template rendered with object=<host> uses that host's site/role. device is only set for Device/VM/VDC; a Site assignment is not advertised as device.

Scope frozen at tip c46ed48.

Merge after: #117
Next: #125

[berlikm]

This PR is part of the zero-touch provisioning feature set described in #121. Please see that issue for the full architecture and motivation.

[berlikm]

Conflict resolution note for rebase

When rebasing this PR after #115 lands, there will be a conflict in nbxsync/utils/sync/hostsync.py on the tag loop line:

• Ours (this PR): for assigned_tag in self.context.get('all_objects', {}).get('tags'):
• Theirs (feat: Site/SiteGroup/Region inheritance, recursive ancestry, exclusion and inherited sync UI #115): for assigned_tag in (self.context.get('all_objects', {}).get('tags', []) or []):

Correct resolution: Take #115's version (or [] normalization). This PR's render(object=sync_target) on the line below merges cleanly — no conflict there.

Verified in the integration-test branch: 1135 tests pass, E2E confirmed.

[berlikm]

Restacked onto the 1.0.5 rebase of #117.

Render-only: device/VM context for Jinja2 tag & hostgroup values, plus UI previews. No change to trigger-dependency behaviour from 1.0.5 (enabled=False by default; hook once after the assignment loop).

Scope frozen at 31d8d6e. Merge after #117; next is #125.

[berlikm]

Follow-up on the 1.0.5 rebase: #102's related-object Jinja aliases are now in this PR (c46ed48).

device / site / tenant / role / device_type / manufacturer are derived from the final render object (the host during sync), not from the assignment row. That way a Role-level template still uses the Device being synced, which #102's device = assigned_object would have gotten wrong for inherited assignments.