Add initial Keycloak setup with custom theme and Docker configuration

- Created .env.example for environment variable configuration.
- Added .gitignore to exclude .env files.
- Introduced docker-compose files for Keycloak and Postgres services.
- Implemented custom Keycloak theme 'drill-luxe' with associated templates and styles.
- Updated README with deployment instructions and repository details.

.env.example

@@ -0,0 +1,6 @@
+POSTGRES_DB=keycloak
+POSTGRES_USER=keycloak_user
+POSTGRES_PASSWORD=r8f\i?71XPB2/tm
+KC_BOOTSTRAP_ADMIN_USERNAME=kc_admin
+KC_BOOTSTRAP_ADMIN_PASSWORD=wVMR6R/S3>q9I?–
+KC_PUBLIC_HOSTNAME=sso.greact.ru