Fix backup feature for local Windows development

- Add --no-reload flag to run_dev.py to prevent env var loss
- Configure SHOPDB_BACKUPS_ROOT in .env for Windows path
- Create local backups directory
- Document local dev setup in backup README
- Fix: Flask auto-reloader was spawning process without env vars

scripts/backup/README.md

@@ -42,6 +42,24 @@ Each backup set includes:
 3. Click **Restore**
 4. System validates schema compatibility and restores database + files
 
+## Local Development Setup
+
+For local dev on Windows, configure a local backup directory:
+
+1. Add to `.env`:
+   ```
+   SHOPDB_BACKUPS_ROOT=C:/Users/YOUR_USERNAME/Documents/github/flask-shopdb/backups
+   ```
+
+2. Create the directory:
+   ```bash
+   mkdir backups
+   ```
+
+3. Restart Flask
+
+Note: Actual backup execution requires Docker (the backup container). The API can queue backups but won't execute them without the sidecar container.
+
 ## First Deployment
 
 On fresh install, `/api/shopdbbackups` returns empty list - this is normal.