feat(ui): add Adaptive Prompt Tuner tab with correction submission UI

- Add pgCorrectedModerationsTable to shared schema
- Create backend corrections module (stats, list, create endpoints)
- Add TunerPanel with Stats, History, and Submit sub-tabs
- Add AuthOverlay gate for Tuner (admin-only, same as Live)
- Set messages as default tab
- Wire Tuner into sidebar, header, and mobile tab bar

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

services/frontend/src/shared/ui/MobileTabBar.tsx

@@ -1,10 +1,11 @@
-import { MessageSquare, Radio } from "lucide-react";
+import { MessageSquare, Radio, SlidersHorizontal } from "lucide-react";
 import type { DashboardTab } from "../../entities/ui/types";
 import { cn } from "../lib/utils";
 
 const tabs: Array<{ id: DashboardTab; label: string; Icon: typeof Radio }> = [
   { id: "live", label: "Live", Icon: Radio },
   { id: "messages", label: "Messages", Icon: MessageSquare },
+  { id: "tuner", label: "Tuner", Icon: SlidersHorizontal },
 ];
 
 interface MobileTabBarProps {