Fix critical startup issue - remove email-validator dependency

- Replace EmailStr with custom email validation using regex
- Remove pydantic[email] dependency to prevent import errors
- Update config to use dynamic database path with proper directory creation
- Improve database session configuration with connection pooling
- Fix application startup failures caused by missing email-validator package

🤖 Generated with Claude Code

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

app/core/config.py

@@ -10,8 +10,17 @@ class Settings(BaseSettings):
     ALGORITHM: str = "HS256"
     ACCESS_TOKEN_EXPIRE_MINUTES: int = 60 * 24 * 8
     
-    DB_DIR: Path = Path("/app/storage/db")
-    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+    # Use relative path from current working directory or absolute path if specified
+    DB_DIR: Path = Path(os.getenv("DB_DIR", "/app/storage/db"))
+    
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        # Ensure the database directory exists
+        self.DB_DIR.mkdir(parents=True, exist_ok=True)
+    
+    @property
+    def SQLALCHEMY_DATABASE_URL(self) -> str:
+        return f"sqlite:///{self.DB_DIR}/db.sqlite"
     
     PAYMENT_PROVIDER_API_URL: str = os.getenv("PAYMENT_PROVIDER_API_URL", "")
     PAYMENT_PROVIDER_API_KEY: str = os.getenv("PAYMENT_PROVIDER_API_KEY", "")

app/db/session.py

@@ -1,16 +1,13 @@
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
-from pathlib import Path
 
-
-DB_DIR = Path("/app/storage/db")
-DB_DIR.mkdir(parents=True, exist_ok=True)
-
-SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+from app.core.config import settings
 
 engine = create_engine(
-    SQLALCHEMY_DATABASE_URL,
-    connect_args={"check_same_thread": False}
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False},
+    pool_pre_ping=True,
+    pool_recycle=300
 )
 
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

app/schemas/user.py

@@ -1,17 +1,27 @@
 from typing import Optional
-from pydantic import BaseModel, EmailStr
+from pydantic import BaseModel, field_validator
 from datetime import datetime
+import re
 
 
 class UserBase(BaseModel):
-    email: Optional[EmailStr] = None
+    email: Optional[str] = None
     username: Optional[str] = None
     is_active: Optional[bool] = True
     is_verified: Optional[bool] = False
 
+    @field_validator('email')
+    @classmethod
+    def validate_email(cls, v):
+        if v is not None:
+            email_pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
+            if not re.match(email_pattern, v):
+                raise ValueError('Invalid email format')
+        return v
+
 
 class UserCreate(UserBase):
-    email: EmailStr
+    email: str
     username: str
     password: str