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/0031_userprofile_enable_automatic_html_snapshots.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.0.2 on 2024-04-01 10:29
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookmarks", "0030_bookmarkasset"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="userprofile",
+            name="enable_automatic_html_snapshots",
+            field=models.BooleanField(default=True),
+        ),
+    ]