saved_snippets: Add backend for saved snippets.

Part of #31227.

zerver/models/saved_snippets.py

@@ -0,0 +1,26 @@
+from typing import Any
+
+from django.conf import settings
+from django.db import models
+from django.utils.timezone import now as timezone_now
+
+from zerver.models.realms import Realm
+from zerver.models.users import UserProfile
+
+
+class SavedSnippet(models.Model):
+    MAX_TITLE_LENGTH = 60
+
+    realm = models.ForeignKey(Realm, on_delete=models.CASCADE)
+    user_profile = models.ForeignKey(UserProfile, on_delete=models.CASCADE)
+    title = models.TextField(max_length=MAX_TITLE_LENGTH)
+    content = models.TextField(max_length=settings.MAX_MESSAGE_LENGTH)
+    date_created = models.DateTimeField(default=timezone_now)
+
+    def to_api_dict(self) -> dict[str, Any]:
+        return {
+            "id": self.id,
+            "title": self.title,
+            "content": self.content,
+            "date_created": int(self.date_created.timestamp()),
+        }