v0.2.0: fix leaked multi-line {# #} comments, add German translation

- Fix template comments rendering as literal text: Django's {# #} tag
  regex (tag_re in django/template/base.py) has no re.DOTALL, so a
  comment spanning multiple lines is never recognized as a tag at all
  and leaks into the rendered output verbatim - exactly what showed up
  under "Elevation". Collapsed all three offending comments to single
  lines. This was also almost certainly the real cause of the "PNG
  could not be generated" report: two of the leaked comments sat
  inside the shared SVG partial, corrupting the exported SVG enough
  that the browser's image decoder rejected it (my own onerror handler
  then showed a misleading CORS-sounding message - the actual bug was
  malformed markup, not cross-origin images).
- Add a German translation (locale/de/), built from every _() and
  {% trans %}/{% blocktrans %} string in the plugin (269 entries,
  cross-checked against the source for completeness). English needs no
  catalog of its own since it's the literal source text; both were
  already listed in NetBox's own language selector.
- Add CHANGELOG.md and bump the version to 0.2.0, covering this and
  every unreleased change so far; will keep bumping per change from
  here on.

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

README.md

@@ -268,6 +268,13 @@ Kabel, Interfaces jenseits der Device-Type-Templates, IP-Adressen, Seriennummern
 Asset-Tags. Geplante Geräte ohne Rolle, ohne Gerätetyp oder ohne Position werden
 übersprungen — welche das sind, zeigt die Bestätigungsseite vor dem Ausrollen an.
 
+## Sprache
+
+Das Plugin ist auf Englisch (Quelltext) und Deutsch übersetzt. Beide Sprachen sind in
+NetBox bereits als Auswahl hinterlegt; die Anzeigesprache stellt man wie gewohnt über
+das Benutzerprofil (Preferences → Language) um — keine zusätzliche Konfiguration nötig.
+Die Übersetzung liegt unter `netbox_rack_concept/locale/de/LC_MESSAGES/`.
+
 ## Berechtigungen
 
 Es gelten die normalen NetBox-Objektberechtigungen: