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/routers/auth.py

@@ -22,7 +22,7 @@ from app.config import settings
 from app.db.engine import get_db
 from app.routers.users import _user_projects, user_to_dict
 from app.services import analytics
-from app.utils.errors import ForbiddenError, ServiceUnavailableError, UnauthorizedError
+from app.utils.errors import ServiceUnavailableError, UnauthorizedError
 from app.utils.ratelimit import limiter
 
 logger = logging.getLogger("procurement.auth")
@@ -78,8 +78,6 @@ async def login(request: Request, payload: LoginRequest, db: AsyncSession = Depe
     claims = await _verify_token(access_token)
     ctx = await context_from_claims(claims, db)
     projects = await _user_projects(db, ctx.user)
-    if ctx.role == "supervisor" and not projects:
-        raise ForbiddenError("پروژه تخصیص داده نشده است — تا زمان تخصیص پروژه، اجازه ورود به سامانه را ندارید")
     await analytics.track(
         "login_success",
         {"username": payload.username, "role": ctx.role},