feat(auth): export new auth functions from middleware package

Part of #12

Author: DevanshuNEU

backend/middleware/__init__.py

@@ -1,4 +1,18 @@
 """Authentication middleware package"""
-from .auth import get_current_user, get_optional_user
+from .auth import (
+    # New unified auth (recommended)
+    AuthContext,
+    require_auth,
+    public_auth,
+    # Legacy (backwards compatibility)
+    get_current_user,
+    get_optional_user,
+)
 
-__all__ = ["get_current_user", "get_optional_user"]
+__all__ = [
+    "AuthContext",
+    "require_auth", 
+    "public_auth",
+    "get_current_user",
+    "get_optional_user",
+]