Improve sso auth flow (#6205)

Co-authored-by: Timshel <timshel@users.noreply.github.com>

migrations/sqlite/2025-08-20-120000_sso_nonce_to_auth/down.sql

@@ -0,0 +1,9 @@
+DROP TABLE IF EXISTS sso_auth;
+
+CREATE TABLE sso_nonce (
+  state               TEXT NOT NULL PRIMARY KEY,
+  nonce               TEXT NOT NULL,
+  verifier            TEXT,
+  redirect_uri        TEXT NOT NULL,
+  created_at          DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
+);