feat: add Playwright configuration and initial e2e test for authentication

- Created Playwright configuration file to set up testing environment.
- Added a new e2e test for user authentication in login.spec.ts.
- Updated tsconfig.node.json to include playwright.config.ts.
- Enhanced vite.config.ts to include API proxying for backend integration.
- Added a placeholder for last run test results in .last-run.json.

backend/app/repositories/users.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import sqlalchemy as sa
+from sqlalchemy.orm import Session
+
+from backend.app.db.models import User
+from backend.app.models import UserCreate
+from backend.app.repositories.base import BaseRepository
+
+
+class UserRepository(BaseRepository[User]):
+    """Data access helpers for user accounts."""
+
+    model = User
+
+    def __init__(self, session: Session) -> None:
+        super().__init__(session)
+
+    def get_by_username(self, username: str) -> User | None:
+        statement = sa.select(self.model).where(sa.func.lower(self.model.username) == username.lower())
+        return self.session.scalar(statement)
+
+    def list_recent(self, limit: int = 50) -> list[User]:
+        statement = sa.select(self.model).order_by(self.model.created_at.desc()).limit(limit)
+        return list(self.session.scalars(statement))
+
+    def create(self, data: UserCreate) -> User:
+        user = User(
+            username=data.username,
+            email=data.email,
+            full_name=data.full_name,
+            password_hash=data.password_hash,
+            role=data.role,
+            preferences=data.preferences,
+        )
+        self.session.add(user)
+        return user