Add backlogger app at /backlogger/ with login protection

Django app with Item model (games/books/films/other categories), CRUD
views, and login-required access. Login page at /accounts/login/ uses
custom dark-themed template consistent with the site design.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backlogger/forms.py

@@ -0,0 +1,46 @@
+from django import forms
+from .models import Item
+
+
+class ItemForm(forms.ModelForm):
+    progress_percent = forms.FloatField(
+        min_value=0,
+        max_value=100,
+        initial=0,
+        widget=forms.NumberInput(attrs={
+            'type': 'range',
+            'min': '0',
+            'max': '100',
+            'step': '1',
+        }),
+    )
+
+    class Meta:
+        model = Item
+        fields = [
+            'category', 'name', 'progress_percent', 'favorite',
+            'hours_played', 'total_hours',
+            'pages_read', 'total_pages',
+            'watched', 'duration_minutes',
+        ]
+        widgets = {
+            'hours_played': forms.NumberInput(attrs={'step': '0.5', 'min': '0'}),
+            'total_hours': forms.NumberInput(attrs={'step': '0.5', 'min': '0'}),
+            'pages_read': forms.NumberInput(attrs={'min': '0'}),
+            'total_pages': forms.NumberInput(attrs={'min': '0'}),
+            'duration_minutes': forms.NumberInput(attrs={'min': '0'}),
+        }
+
+    def clean(self):
+        cleaned_data = super().clean()
+        category = cleaned_data.get('category')
+        if category != Item.GAMES:
+            cleaned_data['hours_played'] = None
+            cleaned_data['total_hours'] = None
+        if category != Item.BOOKS:
+            cleaned_data['pages_read'] = None
+            cleaned_data['total_pages'] = None
+        if category != Item.FILMS:
+            cleaned_data['watched'] = None
+            cleaned_data['duration_minutes'] = None
+        return cleaned_data