Fix dev seed for single-company schema, sync RBAC on startup

- Remove all company_id references from dev-seed.ts (removed in 0021)
- seedPermissions now syncs role-permission assignments for system roles
  when new permissions are added (e.g., vault.view assigned to admin)
- Fix enum migration: use text cast workaround for PostgreSQL's
  "unsafe use of new enum value" error on fresh DB creation

packages/backend/src/db/migrations/0020_repair_default_new.sql

@@ -1 +1,3 @@
-ALTER TABLE "repair_ticket" ALTER COLUMN "status" SET DEFAULT 'new';
+-- Use text cast to avoid the "unsafe use of new enum value" error
+-- when 0019 (ADD VALUE) and this run in the same session
+ALTER TABLE "repair_ticket" ALTER COLUMN "status" SET DEFAULT 'new'::text::repair_ticket_status;