feat: [US-003] Audit and document deploy script data preservation

- Add detailed logging in Deploy-Backend function for data/ preservation
- Update deployment/windows/README.md with "Data Preserved During Deploy" section
- Document data/ directory structure (receipts/, telegram/, cache/)
- Explain preservation mechanism (backup → deploy → restore)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

deployment/windows/README.md

@@ -154,6 +154,56 @@ deploy.sh (Linux)                           │
 
 ---
 
+## Data Preserved During Deploy
+
+During deployment, the following are **automatically preserved** (not overwritten):
+
+### Files Preserved
+
+| Item | Location | Description |
+|------|----------|-------------|
+| `.env` | `backend/.env` | Environment configuration |
+| `data/` | `backend/data/` | All SQLite databases and uploads |
+
+### Data Directory Structure
+
+```
+backend/data/
+├── receipts/           # Data Entry module
+│   ├── receipts*.db    # SQLite database (bonuri, aprobări, workflow)
+│   └── uploads/        # User-uploaded files (PDF/images)
+├── telegram/           # Telegram Bot module
+│   └── telegram*.db    # Bot auth/session data
+└── cache/              # Reports module
+    └── roa2web_cache*.db  # L2 cache (can be regenerated)
+```
+
+### Preservation Mechanism
+
+The `ROA2WEB-Console.ps1` script:
+
+1. **Before deploy**: Copies `data/` to `%TEMP%\roa2web-data-backup-*`
+2. **During deploy**: Deletes and replaces entire `backend/` folder
+3. **After deploy**: Restores `data/` from backup
+
+**Safe to lose** (regenerated automatically):
+- `cache/*.db` - Reports cache, rebuilt on first query
+
+**Critical data** (must be preserved):
+- `receipts/*.db` - User data, approvals, workflow states
+- `telegram/*.db` - Bot authentication tokens
+
+### Manual Backup
+
+```powershell
+# Create manual backup before major operations
+Copy-Item -Path "C:\inetpub\wwwroot\roa2web\backend\data" `
+          -Destination "C:\backups\roa2web-data-$(Get-Date -Format 'yyyyMMdd')" `
+          -Recurse
+```
+
+---
+
 ## Troubleshooting
 
 | Problemă | Verificare | Soluție |