install: backup and restore HorizonOC config.ini on OC pack update

- Copy sd:/config/horizon-oc/config.ini to sd:/.omninx_oc_update before
  update cleanup/copy; restore after Hekate step, then remove the scratch dir.
- Only when INSTALL_MODE_UPDATE and VARIANT_OC.

Made-with: Cursor

source/backup.h

@@ -8,6 +8,12 @@
 
 #define TEMP_BACKUP_PATH "sd:/temp_backup"
 
+/** Live HorizonOC settings (Overclock tool). */
+#define HORIZON_OC_CONFIG_PATH "sd:/config/horizon-oc/config.ini"
+/** Scratch dir during OC-variant update only; removed after successful restore. */
+#define HORIZON_OC_UPDATE_BACKUP_DIR "sd:/.omninx_oc_update"
+#define HORIZON_OC_UPDATE_BACKUP_INI HORIZON_OC_UPDATE_BACKUP_DIR "/config.ini"
+
 // Backup user data (DBI, Tinfoil, prod.keys) before clean install
 int backup_user_data(void);
 
@@ -16,3 +22,10 @@ int restore_user_data(void);
 
 // Clean up temporary backup directory
 int cleanup_backup(void);
+
+// HorizonOC: backup config.ini before OC pack update (update mode only); no-op if missing
+int backup_horizon_oc_config_for_oc_update(void);
+// Restore after file copy; no-op if no backup from this run
+int restore_horizon_oc_config_after_oc_update(void);
+// Delete sd:/.omninx_oc_update after successful restore
+int cleanup_horizon_oc_update_backup(void);