[INIT-001] Initial project setup with Clean Architecture (feat)

- Implemented Clean Architecture with Domain, Application, Infrastructure, Presentation layers
- Added comprehensive project structure following SOLID principles
- Created Kubernetes deployment with Helm charts (HPA, PDB, NetworkPolicy)
- Configured ArgoCD for automated deployment (production + staging)
- Implemented CI/CD pipeline with GitHub Actions
- Added comprehensive documentation (handbook, architecture, coding standards)
- Configured PostgreSQL, Redis, Celery for backend services
- Created modern landing page with Persian fonts (Vazirmatn)
- Added Docker multi-stage build for production
- Configured development tools (pytest, black, flake8, mypy, isort)
- Added pre-commit hooks for code quality
- Implemented Makefile for common operations

src/infrastructure/database/models/base.py

@@ -0,0 +1,51 @@
+"""Base model for all database models.
+
+This module defines the base class that all SQLAlchemy models inherit from.
+"""
+
+from datetime import datetime
+from sqlalchemy import Column, Integer, DateTime
+from sqlalchemy.ext.declarative import declared_attr
+
+from src.config.database import Base as DeclarativeBase
+
+
+class BaseModel(DeclarativeBase):
+    """Base model with common fields.
+    
+    All models should inherit from this class to get:
+    - id (primary key)
+    - created_at
+    - updated_at
+    - Automatic table naming
+    """
+    
+    __abstract__ = True
+    
+    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+    updated_at = Column(
+        DateTime,
+        default=datetime.utcnow,
+        onupdate=datetime.utcnow,
+        nullable=False
+    )
+    
+    @declared_attr
+    def __tablename__(cls) -> str:
+        """Generate table name from class name.
+        
+        Converts PascalCase to snake_case.
+        Example: UserModel -> user_model
+        """
+        import re
+        name = cls.__name__
+        # Convert PascalCase to snake_case
+        name = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)
+        name = re.sub('([a-z0-9])([A-Z])', r'\1_\2', name).lower()
+        return name
+    
+    def __repr__(self) -> str:
+        """String representation."""
+        return f"<{self.__class__.__name__}(id={self.id})>"
+