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/db/init_db.py

@@ -174,7 +174,7 @@ _V26_DDL = [
     """,
     """
     DO $$ BEGIN
-        CREATE TYPE user_role AS ENUM ('pm', 'procurement_manager', 'admin');
+        CREATE TYPE user_role AS ENUM ('pm', 'procurement_manager', 'admin', 'supervisor');
     EXCEPTION WHEN duplicate_object THEN NULL; END $$
     """,
     """