feat: add the ability to make email optional (#994)

backend/resources/migrations/sqlite/20251001115300_optional_email.up.sql

@@ -0,0 +1,40 @@
+PRAGMA foreign_keys = OFF;
+BEGIN;
+
+CREATE TABLE users_new
+(
+    id           TEXT    NOT NULL PRIMARY KEY,
+    created_at   DATETIME,
+    username     TEXT    NOT NULL COLLATE NOCASE UNIQUE,
+    email        TEXT    UNIQUE,
+    first_name   TEXT,
+    last_name    TEXT    NOT NULL,
+    display_name TEXT    NOT NULL,
+    is_admin     NUMERIC NOT NULL DEFAULT FALSE,
+    ldap_id      TEXT,
+    locale       TEXT,
+    disabled     NUMERIC NOT NULL DEFAULT FALSE
+);
+
+INSERT INTO users_new (id, created_at, username, email, first_name, last_name, display_name, is_admin, ldap_id, locale,
+                       disabled)
+SELECT id,
+       created_at,
+       username,
+       email,
+       first_name,
+         last_name,
+         display_name,
+       is_admin,
+       ldap_id,
+       locale,
+       disabled
+FROM users;
+
+DROP TABLE users;
+
+ALTER TABLE users_new
+    RENAME TO users;
+
+COMMIT;
+PRAGMA foreign_keys = ON;