Code refactoring to simplify template data contexts (#55)

* Fix a search filter when no catalogs are returned
* Code refactoring to simplify templates
* Remove duplicated code
* Remove dead code
* More improvements, clean up and add featured items in homepage
* Fix a type and better page navigation

ram/roster/migrations/0039_rollingstock_featured.py

@@ -0,0 +1,21 @@
+# Generated by Django 6.0 on 2025-12-24 13:39
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("roster", "0038_alter_rollingstock_rolling_class"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="rollingstock",
+            name="featured",
+            field=models.BooleanField(
+                default=False,
+                help_text="Featured rolling stock will appear on the homepage",
+            ),
+        ),
+    ]