feat(mentions): overhaul, refactor, notification bubble & window update

Chat tagging:
- Any @user is a visible tag in chat bubbles (the .mention-tag CSS never
  existed, so highlighting was invisible); self/alias mentions get a gold
  emphasis. Fixes cross-room tags not being highlighted.

Mentions window:
- Redesigned: unread count in the header, restyled filter chips + a refresh
  button, CSS-driven list/date-groups, adaptive height (compact when few,
  capped + scroll when many), polished empty state.
- Rows: framed avatar (friends-list head crop so the face is never clipped),
  per-row unread dot, type marker, icon action buttons (goto / remove).
- Re-requests from the server each time it opens.

Autocomplete:
- Never suggests the viewer themselves; suggests room users + online friends +
  aliases.

Notifications:
- Mention toast removed; mentions flow through the client's standard
  notification stream via a dedicated mention bubble (avatar + actions) in the
  default position. EVERY received mention surfaces (independent of the generic
  info-feed toggle, gated only by mentions_ui.enabled).

Refactor (behaviour-preserving):
- Centralised @-token classification in api/mentions/mentionTokens.
- Moved mentionsFormat -> api/mentions, useMentionActions -> hooks/mentions.
- Extracted ChatInputView @-autocomplete into a tested useChatMentions hook +
  pure helper; removed the dead duplicate useMentionAutocomplete.

src/hooks/notification/useNotification.ts

@@ -1,7 +1,7 @@
 import { AchievementNotificationMessageEvent, ActivityPointNotificationMessageEvent, BadgeReceivedEvent, ClubGiftNotificationEvent, ClubGiftSelectedEvent, ConnectionErrorEvent, GetLocalizationManager, GetRoomEngine, GetSessionDataManager, HabboBroadcastMessageEvent, HotelClosedAndOpensEvent, HotelClosesAndWillOpenAtEvent, HotelWillCloseInMinutesEvent, InfoFeedEnableMessageEvent, MaintenanceStatusMessageEvent, ModeratorCautionEvent, ModeratorMessageEvent, MOTDNotificationEvent, NotificationDialogMessageEvent, PetLevelNotificationEvent, PetReceivedMessageEvent, RespectReceivedEvent, RoomEnterEffect, RoomEnterEvent, SimpleAlertMessageEvent, UserBannedMessageEvent, Vector3d, WiredRewardResultMessageEvent } from '@nitrots/nitro-renderer';
 import { useCallback, useState } from 'react';
 import { useBetween } from 'use-between';
-import { GetConfigurationValue, LocalizeBadgeName, LocalizeText, NotificationAlertItem, NotificationAlertType, NotificationBubbleItem, NotificationBubbleType, NotificationConfirmItem, PlaySound, ProductImageUtility, TradingNotificationType } from '../../api';
+import { GetConfigurationValue, IMentionEntry, LocalizeBadgeName, LocalizeText, MentionNotificationBubbleItem, NotificationAlertItem, NotificationAlertType, NotificationBubbleItem, NotificationBubbleType, NotificationConfirmItem, PlaySound, ProductImageUtility, TradingNotificationType } from '../../api';
 import { useMessageEvent } from '../events';
 
 const cleanText = (text: string) => (text && text.length) ? text.replace(/\\r/g, '\r') : '';
@@ -86,6 +86,16 @@ const useNotificationStore = () =>
         });
     }, [ bubblesDisabled ]);
 
+    const showMentionBubble = useCallback((mention: IMentionEntry) =>
+    {
+        // Mentions always surface: they have their own `mentions_ui.enabled` gate
+        // (checked in useMentionMessages) and are intentionally independent of the
+        // generic info-feed toggle, so EVERY received mention shows a bubble.
+        const item = new MentionNotificationBubbleItem(mention);
+
+        setBubbleAlerts(prevValue => [ item, ...prevValue ]);
+    }, []);
+
     const showNotification = (type: string, options: Map<string, string> = null) =>
     {
         if(!options) options = new Map();
@@ -490,7 +500,7 @@ const useNotificationStore = () =>
 
     useMessageEvent<RoomEnterEvent>(RoomEnterEvent, onRoomEnterEvent);
 
-    return { alerts, bubbleAlerts, confirms, simpleAlert, showNitroAlert, showTradeAlert, showConfirm, showSingleBubble, closeAlert, closeBubbleAlert, closeConfirm };
+    return { alerts, bubbleAlerts, confirms, simpleAlert, showNitroAlert, showTradeAlert, showConfirm, showSingleBubble, showMentionBubble, closeAlert, closeBubbleAlert, closeConfirm };
 };
 
 export const useNotificationState = () =>
@@ -508,6 +518,7 @@ export const useNotificationActions = () =>
         showTradeAlert,
         showConfirm,
         showSingleBubble,
+        showMentionBubble,
         closeAlert,
         closeBubbleAlert,
         closeConfirm
@@ -519,6 +530,7 @@ export const useNotificationActions = () =>
         showTradeAlert,
         showConfirm,
         showSingleBubble,
+        showMentionBubble,
         closeAlert,
         closeBubbleAlert,
         closeConfirm