Refactor URL handling to use BASE_URL across the application and add base_url context processor

core/context_processors.py

@@ -0,0 +1,17 @@
+from typing import TYPE_CHECKING
+
+from django.conf import settings
+
+if TYPE_CHECKING:
+    from django.http import HttpRequest
+
+
+def base_url(request: HttpRequest) -> dict[str, str]:
+    """Provide BASE_URL to templates for deterministic absolute URL creation.
+
+    Returns:
+        dict[str, str]: A dictionary containing the BASE_URL.
+    """
+    return {
+        "BASE_URL": getattr(settings, "BASE_URL", ""),
+    }