feat: Add data-entry-app for fiscal receipts with approval workflow

New application for entering fiscal receipts (bonuri fiscale) with:

Backend (FastAPI + SQLModel + Alembic):
- Receipt, ReceiptAttachment, AccountingEntry models
- CRUD operations with async SQLite database
- Workflow: DRAFT → PENDING_REVIEW → APPROVED/REJECTED
- Auto-generation of accounting entries with VAT calculation
- File upload support (images, PDFs)
- Predefined expense types (Fuel, Materials, Office, etc.)
- Nomenclature service for partners, accounts, cash registers

Frontend (Vue.js 3 + PrimeVue + Pinia):
- ReceiptsListView with filters and stats
- ReceiptCreateView with image upload
- ReceiptDetailView with accounting entries
- ReceiptApprovalView for accountant approval

Documentation:
- REQUIREMENTS.md with functional specifications
- ARCHITECTURE.md with technical decisions
- CLAUDE.md for AI assistant guidance

Phase 1 MVP uses SQLite, prepared for Oracle integration in Phase 2.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

data-entry-app/backend/app/services/__init__.py

@@ -0,0 +1,11 @@
+# Business logic services
+from .receipt_service import ReceiptService
+from .nomenclature_service import NomenclatureService
+from .expense_types import EXPENSE_TYPES, ExpenseType
+
+__all__ = [
+    "ReceiptService",
+    "NomenclatureService",
+    "EXPENSE_TYPES",
+    "ExpenseType",
+]