Revert 253c922: restore the PM/RBAC work to the integration

Reverting the production revert so the pm branch can merge cleanly on
top of the restored RBAC base. Conflicts against newer integration work
resolved by combining:
- App.tsx: v7's bot-draft wizard bypass + login returnUrl kept alongside
  the supervisor gating (no-project block screen, panel scoping)
- LoginPage: returnUrl navigation kept, supervisor routing added
- migration.sql: bot_drafts table kept, unified-projects ALTERs restored

backend/app/routers/standard_conversions.py

@@ -3,6 +3,7 @@ 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 StandardConversion
 from app.schemas.catalog import StandardConversionCreate, StandardConversionUpdate
@@ -11,6 +12,7 @@ from app.utils.pagination import paginate
 from app.utils.serialization import to_iso
 
 router = APIRouter(prefix="/standard-conversions", tags=["standard-conversions"])
+_procurement_writer = require_role("admin", "procurement_manager")
 
 
 def sc_to_dict(sc: StandardConversion) -> dict:
@@ -41,7 +43,11 @@ async def list_standard_conversions(
 
 
 @router.post("", status_code=201)
-async def create_standard_conversion(payload: StandardConversionCreate, db: AsyncSession = Depends(get_db)):
+async def create_standard_conversion(
+    payload: StandardConversionCreate,
+    db: AsyncSession = Depends(get_db),
+    _auth=Depends(_procurement_writer),
+):
     duplicate = await db.scalar(
         select(StandardConversion.id).where(
             StandardConversion.from_unit == payload.from_unit,
@@ -67,7 +73,12 @@ async def get_standard_conversion(sc_id, db: AsyncSession = Depends(get_db)):
 
 
 @router.patch("/{sc_id}")
-async def update_standard_conversion(sc_id, payload: StandardConversionUpdate, db: AsyncSession = Depends(get_db)):
+async def update_standard_conversion(
+    sc_id,
+    payload: StandardConversionUpdate,
+    db: AsyncSession = Depends(get_db),
+    _auth=Depends(_procurement_writer),
+):
     sc = await db.get(StandardConversion, sc_id)
     if sc is None:
         raise NotFoundError("تبدیل استاندارد یافت نشد")
@@ -94,7 +105,11 @@ async def update_standard_conversion(sc_id, payload: StandardConversionUpdate, d
 
 
 @router.delete("/{sc_id}")
-async def delete_standard_conversion(sc_id, db: AsyncSession = Depends(get_db)):
+async def delete_standard_conversion(
+    sc_id,
+    db: AsyncSession = Depends(get_db),
+    _auth=Depends(_procurement_writer),
+):
     sc = await db.get(StandardConversion, sc_id)
     if sc is None:
         raise NotFoundError("تبدیل استاندارد یافت نشد")