feat: add database snapshot for schema changes

- Created a snapshot to reflect the updated database schema, including new tables `api_keys`, `audit_logs`, `categories`, `comments`, `contents`, and related relationships.
- Includes indexes, unique constraints, and foreign key definitions.

backend/.migrations/meta/_journal.json

@@ -57,6 +57,13 @@
       "when": 1769605995410,
       "tag": "0007_melodic_synch",
       "breakpoints": true
+    },
+    {
+      "idx": 8,
+      "version": "7",
+      "when": 1769696731978,
+      "tag": "0008_bitter_darwin",
+      "breakpoints": true
     }
   ]
 }