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/test/java/com/cameleer3/server/app/AbstractClickHouseIT.java

@@ -56,7 +56,7 @@ public abstract class AbstractClickHouseIT {
         }
 
         // Load all schema files in order
-        String[] schemaFiles = {"01-schema.sql", "02-search-columns.sql", "03-users.sql", "04-oidc-config.sql"};
+        String[] schemaFiles = {"01-schema.sql", "02-search-columns.sql", "03-users.sql", "04-oidc-config.sql", "05-oidc-auto-signup.sql"};
 
         try (Connection conn = DriverManager.getConnection(
                 CLICKHOUSE.getJdbcUrl(),