ERP Local Agent 1.4.0

Existing storage, WebSocket tunnel, Tally and client .act functionality are preserved.

Local dashboard:
  http://127.0.0.1:8788
  or run open_dashboard.bat

Updates:
  - The agent checks the ERP for new versions automatically.
  - Updates are NOT installed automatically.
  - Open the local dashboard, Download Update, then Install Downloaded Update.
  - .env, .venv, data, logs and client storage are preserved during update.

Local operational database:
  data\agent.db

Client accounting .act databases remain separate under the configured STORAGE_ROOT.

Phase 2: client/registration to Tally company mapping is supported using Tally GUID.

Phase 3: read-only Tally accounting master sync (Groups, Ledgers, Voucher Types, Stock Groups/Categories/Items, Units and Cost Centres/Categories) into client .act storage.

Version 1.5.0: Phase 4 read-only Tally transaction synchronization (vouchers, ledger/inventory entries, bill/cost-centre/bank allocations) with raw voucher XML preservation.
