revert: restore production to the state before 730d0bd (PM/RBAC work moved to 'pm')

Their three commits (730d0bd, 5a9b543, 387edfb) reached production by push and
auto-deployed. 387edfb expects a users.username column that the live database does
not have, so POST /api/v1/auth/login was returning HTTP 500. Their schema changes
never applied either (projects still has only id, name, description, start_date,
pm_user_id, created_at), so nothing depends on the reverted code.

This commit sets the tree back to exactly a02b3ea — verified with git diff against
it — while keeping history linear: the work itself is preserved on 'pm' at 387edfb.

backend/app/schemas/procurement.py

@@ -44,19 +44,14 @@ class SupplierMaterialCreate(APIModel):
 
 class ProjectCreate(APIModel):
     name: str = Field(min_length=1)
-    location: str | None = None
-    project_manager: str | None = None
     description: str | None = None
     start_date: date | None = None
 
 
 class ProjectUpdate(APIModel):
     name: str | None = Field(default=None, min_length=1)
-    location: str | None = None
-    project_manager: str | None = None
     description: str | None = None
     start_date: date | None = None
-    status: str | None = None
     # PM assignment (1:N — one PM per project, a PM may own many projects).
     # Admin / procurement manager only; None unassigns this project's PM.
     pm_user_id: UUID | None = None
@@ -208,13 +203,13 @@ class UserCreate(APIModel):
     last_name: str = ""
     phone: str | None = None
     casdoor_id: str | None = None
-    role: Literal["pm", "procurement_manager", "admin", "supervisor"] | None = None
+    role: Literal["pm", "procurement_manager", "admin"] | None = None
 
 
 class UserRoleUpdate(APIModel):
     """role=None revokes the role (and any project assignment)."""
 
-    role: Literal["pm", "procurement_manager", "admin", "supervisor"] | None = None
+    role: Literal["pm", "procurement_manager", "admin"] | None = None
 
 
 class UserProjectUpdate(APIModel):