Add ALTER TABLE migration for auto_signup column on existing ClickHouse

The CREATE TABLE IF NOT EXISTS won't add new columns to an existing table.
Add 05-oidc-auto-signup.sql with ALTER TABLE ADD COLUMN IF NOT EXISTS and
register it in ClickHouseConfig startup schema + test init.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/config/ClickHouseConfig.java

@@ -27,7 +27,8 @@ public class ClickHouseConfig {
     private static final Logger log = LoggerFactory.getLogger(ClickHouseConfig.class);
     private static final String[] SCHEMA_FILES = {
             "clickhouse/01-schema.sql", "clickhouse/02-search-columns.sql",
-            "clickhouse/03-users.sql", "clickhouse/04-oidc-config.sql"
+            "clickhouse/03-users.sql", "clickhouse/04-oidc-config.sql",
+            "clickhouse/05-oidc-auto-signup.sql"
     };
 
     private final DataSource dataSource;