Archive snapshots of websites locally (#672)

* Add basic HTML snapshots

* Implement asset list

* Add snapshot creation tests

* Add deletion tests

* Show file size

* Remove snapshots

* Create new snapshots

* Switch to single-file

* CSS tweak

* Remove auto refresh

* Show delete link when there is no file yet

* Add current date to display name

* Add flag for snapshot support

* Add option for disabling automatic snapshots

* Make snapshots sharable

* Document image variants

* Update README.md

* Add migrations

* Fix tests

bookmarks/migrations/0032_html_snapshots_hint_toast.py

@@ -0,0 +1,34 @@
+# Generated by Django 5.0.2 on 2024-04-01 12:17
+
+from django.db import migrations
+from django.contrib.auth import get_user_model
+
+from bookmarks.models import Toast
+
+User = get_user_model()
+
+
+def forwards(apps, schema_editor):
+
+    for user in User.objects.all():
+        toast = Toast(
+            key="html_snapshots_hint",
+            message="This version adds a new feature for archiving snapshots of websites locally. To use it, you need to switch to a different Docker image. See the installation instructions on GitHub for details.",
+            owner=user,
+        )
+        toast.save()
+
+
+def reverse(apps, schema_editor):
+    Toast.objects.filter(key="bookmark_list_actions_hint").delete()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookmarks", "0031_userprofile_enable_automatic_html_snapshots"),
+    ]
+
+    operations = [
+        migrations.RunPython(forwards, reverse),
+    ]