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/scripts/ROA2WEB-Console.ps1

@@ -817,7 +817,10 @@ function Deploy-Backend {
             $dataTempPath = Join-Path $env:TEMP "roa2web-data-backup-$(Get-Date -Format 'yyyyMMddHHmmss')"
             $dataBackup = $null
             if (Test-Path $dataDir) {
-                Write-Info "Preserving data directory (SQLite databases, uploads, cache)"
+                Write-Info "Preserving data directory: receipts.db, telegram.db, cache, uploads"
+                Write-Info "  - receipts/: Data Entry SQLite database (receipts, approvals)"
+                Write-Info "  - telegram/: Telegram bot auth/session database"
+                Write-Info "  - cache/: Reports L2 cache database"
                 Copy-Item -Path $dataDir -Destination $dataTempPath -Recurse -Force
                 $dataBackup = $dataTempPath
             }