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

portal/shell/context.py

@@ -0,0 +1,37 @@
+from django.utils.translation import gettext_lazy as _
+
+from . import menu, preferences
+
+THEME_OPTIONS = (
+    ("light", _("Light")),
+    ("dark", _("Dark")),
+    ("system", _("System")),
+)
+LANGUAGE_OPTIONS = (("de", "Deutsch"), ("en", "English"))
+FORM_OPTIONS = (("sie", "Sie"), ("du", "du"))
+
+
+def initials(name: str) -> str:
+    words = [w for w in name.split() if w]
+    if not words:
+        return "?"
+    letters = words[0][0] + (words[-1][0] if len(words) > 1 else "")
+    return letters.upper()
+
+
+def shell(request):
+    """Menu, preferences and the values the base layout needs."""
+    prefs = getattr(request, "preferences", preferences.Preferences())
+    portal_user = getattr(request, "portal_user", None)
+    context = {
+        "preferences": prefs,
+        "html_lang": prefs.language,
+        "theme_options": THEME_OPTIONS,
+        "language_options": LANGUAGE_OPTIONS,
+        "form_options": FORM_OPTIONS,
+        "portal_user": portal_user,
+    }
+    if portal_user is not None:
+        context["menu_groups"] = menu.for_user(portal_user, request.path)
+        context["initials"] = initials(portal_user.display_name)
+    return context