✨ feat(auth): add password length validation

- introduce password_too_long function to check bcrypt's 72-byte limit
- update registration and login to handle passwords exceeding limit

app/auth.py

@@ -7,6 +7,7 @@ from sqlmodel import Session, select
 from .db import get_session
 from .models import User
 
+BCRYPT_MAX_BYTES = 72
 pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
 
 
@@ -20,6 +21,14 @@ def verify_password(plain_password: str, hashed_password: str) -> bool:
     return pwd_context.verify(plain_password, hashed_password)
 
 
+def password_too_long(password: str) -> bool:
+    """Return True if password exceeds bcrypt's 72-byte limit."""
+    try:
+        return len(password.encode("utf-8")) > BCRYPT_MAX_BYTES
+    except Exception:
+        return True
+
+
 def get_current_user(
     request: Request,
     session: Session = Depends(get_session),