feat(v2): 13 improvements — functional, visual, UX, backend

Functional:
1. Chat: "▼ New messages below" indicator when scrolled up, click to jump
2. Combat stats: "Clear Session" button (red, with confirm dialog)
3. Inventory: live updates via inventory_delta WS (re-fetches on change)
4. Inventory: real mana time from equipment_cantrip_state WS (live
   countdown with state dot: green=active, red=inactive, yellow=unknown)

Visual:
5. Thin separator line between tool links and sort buttons
6. Selected player row highlighted with darker background (#2a3344)
7. Scroll-to-top button (▲) appears when scrolled past 200px in player list

UX:
8. Double-click player dot on map opens their chat window
9. Right-click player dot shows context menu (Chat/Stats/Inv/Char/Combat/Radar)
10. Ctrl+D keyboard shortcut toggles between map and dashboard views
11. Sound notification on rare drops (880Hz sine beep via Web Audio API)

Backend:
12. Deep-merge lifetime offense/defense per element — accumulates
    total_attacks, failed_attacks, crits, damage per AttackType×Element
    instead of overwriting with latest session data
13. Startup cleanup: deletes stale combat_stats records from before
    the lifetime fix (pre-2026-04-14T09:00Z)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/hooks/useLiveData.ts

@@ -14,6 +14,8 @@ export interface DashboardState {
   recentRares: RareMessage[];
   chatMessages: Map<string, Array<{ text: string; color?: number; timestamp: string }>>;
   nearbyObjects: Map<string, any>;
+  inventoryVersion: number;
+  equipmentCantrips: Map<string, any>;
   socketRef: React.RefObject<WebSocket | null>;
 }
 
@@ -23,10 +25,11 @@ export function useLiveData(): DashboardState {
   const [totalRares, setTotalRares] = useState(0);
   const [totalKills, setTotalKills] = useState(0);
   const [recentRares, setRecentRares] = useState<RareMessage[]>([]);
-  // Chat messages stored in ref to avoid re-renders on every message.
-  // A counter state triggers re-render only when needed.
   const chatMessagesRef = useRef(new Map<string, Array<{ text: string; color?: number; timestamp: string }>>());
   const [chatVersion, setChatVersion] = useState(0);
+  const [inventoryVersion, setInventoryVersion] = useState(0);
+  const equipmentCantripRef = useRef(new Map<string, any>());
+  const [equipCantripVersion, setEquipCantripVersion] = useState(0);
   const [nearbyObjects, setNearbyObjects] = useState<Map<string, any>>(new Map());
   const charsRef = useRef(characters);
   charsRef.current = characters;
@@ -57,6 +60,14 @@ export function useLiveData(): DashboardState {
     } else if (msg.type === 'rare') {
       const r = msg as RareMessage;
       setRecentRares(prev => [r, ...prev].slice(0, 50));
+    } else if (msg.type === 'inventory_delta') {
+      const d = msg as unknown as { character_name: string };
+      // Bump inventory version so open inventory windows can re-fetch
+      setInventoryVersion(v => v + 1);
+    } else if (msg.type === 'equipment_cantrip_state') {
+      const ecs = msg as unknown as { character_name: string; items: any[]; timestamp: string };
+      equipmentCantripRef.current.set(ecs.character_name, ecs);
+      setEquipCantripVersion(v => v + 1);
     } else if (msg.type === 'dungeon_map') {
       // Cache dungeon map data for radar rendering (stored on window for canvas access)
       const dm = msg as unknown as { landblock: string; z_levels: any[] };
@@ -169,5 +180,8 @@ export function useLiveData(): DashboardState {
   // eslint-disable-next-line react-hooks/exhaustive-deps
   const chatMessages = useMemo(() => chatMessagesRef.current, [chatVersion]);
 
-  return { characters, serverHealth, totalRares, totalKills, recentRares, chatMessages, nearbyObjects, socketRef };
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  const equipmentCantrips = useMemo(() => equipmentCantripRef.current, [equipCantripVersion]);
+
+  return { characters, serverHealth, totalRares, totalKills, recentRares, chatMessages, nearbyObjects, inventoryVersion, equipmentCantrips, socketRef };
 }