Fix dev stack startup: seed path, missing migration, passlib/bcrypt incompatibility

- python -m scripts.seed (module mode) fixes ModuleNotFoundError
- Add scripts/__init__.py to make scripts/ a proper package
- Generate initial Alembic migration for users table
- Replace passlib with direct bcrypt>=4.0 (passlib unmaintained, broken with bcrypt 4.x)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/core/security.py

@@ -1,19 +1,17 @@
 from datetime import datetime, timedelta, timezone
 
+import bcrypt
 from jose import jwt
-from passlib.context import CryptContext
 
 from app.core.config import settings
 
-pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
-
 
 def hash_password(password: str) -> str:
-    return pwd_context.hash(password)
+    return bcrypt.hashpw(password.encode(), bcrypt.gensalt()).decode()
 
 
 def verify_password(plain: str, hashed: str) -> bool:
-    return pwd_context.verify(plain, hashed)
+    return bcrypt.checkpw(plain.encode(), hashed.encode())
 
 
 def create_access_token(subject: str) -> str: