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/line_items.py

@@ -3,7 +3,6 @@ from fastapi import APIRouter, Depends, Query
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.auth import require_role
 from app.db.engine import get_db
 from app.models.catalog import Material, Unit
 from app.models.procurement import ItemDecision, LineItem, Quote
@@ -15,7 +14,6 @@ from app.utils.errors import ConflictError, NotFoundError
 from app.utils.pagination import paginate, sort_query
 
 router = APIRouter(prefix="/quotes/{quote_id}/line-items", tags=["line-items"])
-_procurement_writer = require_role("admin", "procurement_manager")
 
 
 async def _quote_or_404(db: AsyncSession, quote_id) -> Quote:
@@ -52,12 +50,7 @@ async def list_line_items(
 
 
 @router.post("", status_code=201)
-async def create_line_item(
-    quote_id,
-    payload: LineItemCreate,
-    db: AsyncSession = Depends(get_db),
-    _auth=Depends(_procurement_writer),
-):
+async def create_line_item(quote_id, payload: LineItemCreate, db: AsyncSession = Depends(get_db)):
     async with db.begin():
         quote = await _quote_or_404(db, quote_id)
         if quote.status != "offered":
@@ -96,11 +89,7 @@ async def get_line_item(
 
 @router.patch("/{line_item_id}")
 async def update_line_item(
-    quote_id,
-    line_item_id,
-    payload: LineItemUpdate,
-    db: AsyncSession = Depends(get_db),
-    _auth=Depends(_procurement_writer),
+    quote_id, line_item_id, payload: LineItemUpdate, db: AsyncSession = Depends(get_db)
 ):
     li = await _line_item_or_404(db, quote_id, line_item_id)
     quote = await _quote_or_404(db, quote_id)
@@ -142,12 +131,7 @@ async def update_line_item(
 
 
 @router.delete("/{line_item_id}")
-async def delete_line_item(
-    quote_id,
-    line_item_id,
-    db: AsyncSession = Depends(get_db),
-    _auth=Depends(_procurement_writer),
-):
+async def delete_line_item(quote_id, line_item_id, db: AsyncSession = Depends(get_db)):
     li = await _line_item_or_404(db, quote_id, line_item_id)
     quote = await _quote_or_404(db, quote_id)
     if quote.status != "offered":