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/item_termsheets.py

@@ -7,6 +7,7 @@ from fastapi import APIRouter, Depends
 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.procurement import (
     ItemDecision,
@@ -23,6 +24,7 @@ router = APIRouter(
     prefix="/quotes/{quote_id}/line-items/{line_item_id}/termsheets",
     tags=["item-termsheets"],
 )
+_procurement_writer = require_role("admin", "procurement_manager")
 
 
 async def _line_item_or_404(db: AsyncSession, quote_id, line_item_id) -> LineItem:
@@ -58,7 +60,11 @@ async def list_item_termsheets(quote_id, line_item_id, db: AsyncSession = Depend
 
 @router.post("", status_code=201)
 async def create_item_termsheet(
-    quote_id, line_item_id, payload: ItemTermsheetCreate, db: AsyncSession = Depends(get_db)
+    quote_id,
+    line_item_id,
+    payload: ItemTermsheetCreate,
+    db: AsyncSession = Depends(get_db),
+    _auth=Depends(_procurement_writer),
 ):
     async with db.begin():
         li = await _line_item_or_404(db, quote_id, line_item_id)
@@ -93,7 +99,12 @@ async def create_item_termsheet(
 
 @router.patch("/{item_termsheet_id}")
 async def update_item_termsheet(
-    quote_id, line_item_id, item_termsheet_id, payload: ItemTermsheetUpdate, db: AsyncSession = Depends(get_db)
+    quote_id,
+    line_item_id,
+    item_termsheet_id,
+    payload: ItemTermsheetUpdate,
+    db: AsyncSession = Depends(get_db),
+    _auth=Depends(_procurement_writer),
 ):
     li = await _line_item_or_404(db, quote_id, line_item_id)
     quote = await db.get(Quote, quote_id)
@@ -114,7 +125,11 @@ async def update_item_termsheet(
 
 @router.delete("/{item_termsheet_id}")
 async def delete_item_termsheet(
-    quote_id, line_item_id, item_termsheet_id, db: AsyncSession = Depends(get_db)
+    quote_id,
+    line_item_id,
+    item_termsheet_id,
+    db: AsyncSession = Depends(get_db),
+    _auth=Depends(_procurement_writer),
 ):
     it = await db.scalar(
         select(ItemTermsheet).where(ItemTermsheet.id == item_termsheet_id, ItemTermsheet.line_item_id == line_item_id)