feat: manage branding profiles in the NetBox UI

New BrandingProfile model (migration 0001) with logo upload, color
pickers, font, Word template upload, table style and extra CSS, plus
list/edit/delete views, an HTML preview and a menu entry with add
button. Access is controlled via the model's Django permissions.

Profiles from the database are offered first in the export form (the
default profile preselected); profiles from PLUGINS_CONFIG still work.

Bump version to 0.2.0 - requires "manage.py migrate".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

netbox_customer_export/navigation.py

@@ -1,4 +1,4 @@
-from netbox.plugins import PluginMenuItem
+from netbox.plugins import PluginMenuButton, PluginMenuItem
 
 menu_items = (
     PluginMenuItem(
@@ -6,4 +6,17 @@ menu_items = (
         link_text="Kundendokumentation",
         permissions=["dcim.view_site"],
     ),
+    PluginMenuItem(
+        link="plugins:netbox_customer_export:branding_list",
+        link_text="Branding-Profile",
+        permissions=["netbox_customer_export.view_brandingprofile"],
+        buttons=(
+            PluginMenuButton(
+                link="plugins:netbox_customer_export:branding_add",
+                title="Hinzufügen",
+                icon_class="mdi mdi-plus-thick",
+                permissions=["netbox_customer_export.add_brandingprofile"],
+            ),
+        ),
+    ),
 )