feat: honor images-only/labels-only rack view mode in offline SVG export

The rack elevation page's "Bilder und Beschriftungen" dropdown only
toggles CSS visibility client-side after the browser already has the
SVG, so a freshly server-rendered export had no way to know which mode
was selected and always exported everything.

apply_rack_view_mode() replicates that filtering server-side by
removing the .label text elements (images-only) or the .device-image /
.device-image-label elements (labels-only) from the parsed SVG.
RackElevationOfflineSVGView now accepts a ?view= query param, and the
rack detail page panel syncs its download links to the page's own
"select.rack-view" dropdown so the exported file matches what's
currently shown.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

netbox_utilities/__init__.py

@@ -1,6 +1,6 @@
 from netbox.plugins import PluginConfig, get_plugin_config
 
-__version__ = "0.11.4"
+__version__ = "0.12.0"
 
 
 class NetBoxUtilitiesConfig(PluginConfig):