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/db/database.py

@@ -0,0 +1,49 @@
+"""Database configuration and session management using SQLModel."""
+
+from pathlib import Path
+from typing import AsyncGenerator
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
+from sqlalchemy.orm import sessionmaker
+from sqlmodel import SQLModel
+
+from app.config import settings
+
+
+# Create async engine
+engine = create_async_engine(
+    settings.database_url,
+    echo=settings.debug,
+    future=True,
+)
+
+# Create async session factory
+async_session_maker = sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+async def init_db() -> None:
+    """Initialize database - create tables if they don't exist."""
+    # Ensure data directory exists
+    db_path = Path(settings.sqlite_database_path)
+    db_path.parent.mkdir(parents=True, exist_ok=True)
+
+    async with engine.begin() as conn:
+        await conn.run_sync(SQLModel.metadata.create_all)
+
+
+async def get_session() -> AsyncGenerator[AsyncSession, None]:
+    """Get async database session for dependency injection."""
+    async with async_session_maker() as session:
+        try:
+            yield session
+        finally:
+            await session.close()
+
+
+# Convenience function for manual session usage
+async def get_db_session() -> AsyncSession:
+    """Get a new database session (manual management)."""
+    return async_session_maker()