feat: add support for Postgres database provider (#79)

backend/migrations/sqlite/20240820205521_multiple_callback_urls.down.sql

@@ -0,0 +1,23 @@
+create table oidc_clients
+(
+    id            TEXT not null primary key,
+    created_at    DATETIME,
+    name          TEXT,
+    secret        TEXT,
+    callback_url  TEXT,
+    image_type    TEXT,
+    created_by_id TEXT
+        references users
+);
+
+insert into oidc_clients(id, created_at, name, secret, callback_url, image_type, created_by_id)
+select id,
+       created_at,
+       name,
+       secret,
+       json_extract(callback_urls, '$[0]'),
+       image_type,
+       created_by_id
+from oidc_clients_dg_tmp;
+
+drop table oidc_clients_dg_tmp;