feat: add page shell, preferences and translations

Base layout with top bar, role-based menu, profile menu and phone layout; theme, language and German form of address kept in cookies; German formal, German informal and English text; Fluent avatar bundled in the image by a Node build stage; placeholder pages for the Publisher and Admin groups.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N3t4WL7bd9bdHHNjEsxzqC

uv.lock

@@ -234,6 +234,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/40/9e/2b38731e0fc536806f16490e1a12d7f0dc2a1235aa8cc07bcc75416a7daa/pluggy-1.7.0-py3-none-any.whl", hash = "sha256:7dd7b0d8832ba3cb632c306926ded123429211b83641b35dc5c41ad2d34f9bec", size = 27082, upload-time = "2026-10-15T09:50:56.808Z" },
 ]
 
+[[package]]
+name = "polib"
+version = "1.2.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/10/9a/79b1067d27e38ddf84fe7da6ec516f1743f31f752c6122193e7bce38bdbf/polib-1.2.0.tar.gz", hash = "sha256:f3ef94aefed6e183e342a8a269ae1fc4742ba193186ad76f175938621dbfc26b", size = 161658, upload-time = "2023-02-23T17:53:56.873Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/6b/99/45bb1f9926efe370c6dbe324741c749658e44cb060124f28dad201202274/polib-1.2.0-py2.py3-none-any.whl", hash = "sha256:1c77ee1b81feb31df9bca258cbc58db1bbb32d10214b173882452c73af06d62d", size = 20634, upload-time = "2023-02-23T17:53:59.919Z" },
+]
+
 [[package]]
 name = "pyasn1"
 version = "0.6.4"
@@ -389,6 +398,7 @@ dependencies = [
 
 [package.dev-dependencies]
 dev = [
+    { name = "polib" },
     { name = "pytest" },
     { name = "pytest-django" },
     { name = "pytest-env" },
@@ -408,6 +418,7 @@ requires-dist = [
 
 [package.metadata.requires-dev]
 dev = [
+    { name = "polib", specifier = ">=1.2.0" },
     { name = "pytest", specifier = ">=8" },
     { name = "pytest-django", specifier = ">=4.9" },
     { name = "pytest-env", specifier = ">=1.1" },