Clear lint warnings from the audit branch (deps + extract NotFound)

- CreationWizard: add sys.skills to the loader effect's deps (stable singleton).
- Extract NotFound to src/app/NotFound.tsx so router.tsx no longer trips
  react-refresh/only-export-components.

Branch is now warning-clean (the 3 remaining eslint errors are pre-existing on master,
in files this branch does not touch).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/features/characters/builder/CreationWizard.tsx

@@ -134,7 +134,8 @@ export function CreationWizard({ campaign, onClose }: { campaign: Campaign; onCl
       void loadPf2e('backgrounds').then((bs) => on && setBackgrounds(dedupeByName(bs.map((b) => ({ name: String(b.name), desc: briefOverview(String((b.description ?? b.text) ?? '')) })))));
     }
     return () => { on = false; };
-  }, [system]);
+    // sys.skills is a stable singleton keyed by `system`, so `system` covers it.
+  }, [system, sys.skills]);
 
   // ---- selections ----
   const [step, setStep] = useState(0);