feat: allow uppercase usernames (#958)

backend/resources/migrations/postgres/20250829120000_user_display_name.down.sql

@@ -1 +0,0 @@
-ALTER TABLE users DROP COLUMN display_name;

backend/resources/migrations/postgres/20250829120000_user_display_name.up.sql

@@ -1,6 +0,0 @@
-ALTER TABLE users ADD COLUMN display_name TEXT;
-
-UPDATE users
-SET display_name = trim(coalesce(first_name,'') || ' ' || coalesce(last_name,''));
-
-ALTER TABLE users ALTER COLUMN display_name SET NOT NULL;

backend/resources/migrations/postgres/20250917170000_user_display_name_and_username.down.sql

@@ -0,0 +1,3 @@
+ALTER TABLE users DROP COLUMN display_name;
+
+ALTER TABLE users ALTER COLUMN username TYPE TEXT;

backend/resources/migrations/postgres/20250917170000_user_display_name_and_username.up.sql

@@ -0,0 +1,6 @@
+ALTER TABLE users ADD COLUMN display_name TEXT;
+UPDATE users SET display_name = trim(coalesce(first_name,'') || ' ' || coalesce(last_name,''));
+ALTER TABLE users ALTER COLUMN display_name SET NOT NULL;
+
+CREATE EXTENSION IF NOT EXISTS citext;
+ALTER TABLE users ALTER COLUMN username TYPE CITEXT COLLATE "C";

backend/resources/migrations/sqlite/20250917170000_user_display_name_and_username.up.sql

@@ -5,7 +5,7 @@ CREATE TABLE users_new
 (
     id           TEXT    NOT NULL PRIMARY KEY,
     created_at   DATETIME,
-    username     TEXT    NOT NULL UNIQUE,
+    username     TEXT    NOT NULL COLLATE NOCASE UNIQUE,
     email        TEXT    NOT NULL UNIQUE,
     first_name   TEXT,
     last_name    TEXT    NOT NULL,