Normalize compose host bind mount paths

doc/operations-and-configuration.md

@@ -10,16 +10,17 @@
 - `worker` (RQ worker via `python -m app.worker.run_worker`)
 - `frontend` (Vite React UI)
 
-Persistent volumes:
-- `db-data`
-- `redis-data`
-- `dcm-storage`
-- `typesense-data`
+Persistent host bind mounts (default root `./data`, overridable with `DCM_DATA_DIR`):
+- `${DCM_DATA_DIR:-./data}/db-data`
+- `${DCM_DATA_DIR:-./data}/redis-data`
+- `${DCM_DATA_DIR:-./data}/storage`
+- `${DCM_DATA_DIR:-./data}/typesense-data`
 
 Reset all persisted runtime data:
 
 ```bash
-docker compose down -v
+docker compose down
+rm -rf ${DCM_DATA_DIR:-./data}
 ```
 
 ## Core Commands
@@ -44,14 +45,14 @@ docker compose logs -f
 
 ## Host Bind Mounts
 
-If you replace Docker named volumes with host bind mounts (for example `./data/storage:/data/storage`), ensure host directories exist and are writable by the backend runtime user.
+Compose is configured with host bind mounts for persistent data. Ensure host directories exist and are writable by the backend runtime user.
 
 Backend and worker run as non-root user `uid=10001` inside containers. For host-mounted storage paths:
 
 ```bash
-mkdir -p ./data/storage
-sudo chown -R 10001:10001 ./data/storage
-sudo chmod -R u+rwX,g+rwX ./data/storage
+mkdir -p ${DCM_DATA_DIR:-./data}/storage
+sudo chown -R 10001:10001 ${DCM_DATA_DIR:-./data}/storage
+sudo chmod -R u+rwX,g+rwX ${DCM_DATA_DIR:-./data}/storage
 ```
 
 If permissions are incorrect, API startup fails with errors similar to: