[split-required] Split website + studio-v2 monoliths (Phase 3 continued)

Website (14 monoliths split):
- compliance/page.tsx (1,519 → 9), docs/audit (1,262 → 20)
- quality (1,231 → 16), alerts (1,203 → 10), docs (1,202 → 11)
- i18n.ts (1,173 → 8 language files)
- unity-bridge (1,094 → 12), backlog (1,087 → 6)
- training (1,066 → 8), rag (1,063 → 8)
- Deleted index_original.ts (4,899 LOC dead backup)

Studio-v2 (5 monoliths split):
- meet/page.tsx (1,481 → 9), messages (1,166 → 9)
- AlertsB2BContext.tsx (1,165 → 5 modules)
- alerts-b2b/page.tsx (1,019 → 6), korrektur/archiv (1,001 → 6)

All existing imports preserved. Zero new TypeScript errors.

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

studio-v2/app/messages/_components/useMessagesPage.ts

@@ -0,0 +1,166 @@
+'use client'
+
+import { useState, useEffect, useMemo } from 'react'
+import {
+  useMessages,
+  formatMessageDate,
+  type Conversation,
+  type Message,
+  type Contact,
+} from '@/lib/MessagesContext'
+
+export function useMessagesPage() {
+  const messagesCtx = useMessages()
+  const {
+    contacts,
+    conversations,
+    messages,
+    templates,
+    unreadCount,
+    recentConversations,
+    sendMessage,
+    markAsRead,
+    createConversation,
+    addReaction,
+    deleteMessage,
+    pinConversation,
+    muteConversation,
+    currentConversationId,
+    setCurrentConversationId,
+  } = messagesCtx
+
+  const [messageInput, setMessageInput] = useState('')
+  const [sendWithEmail, setSendWithEmail] = useState(false)
+  const [isSending, setIsSending] = useState(false)
+  const [showNewConversation, setShowNewConversation] = useState(false)
+  const [showEmojiPicker, setShowEmojiPicker] = useState(false)
+  const [showTemplates, setShowTemplates] = useState(false)
+  const [showContactInfo, setShowContactInfo] = useState(false)
+  const [searchQuery, setSearchQuery] = useState('')
+  const [contextMenu, setContextMenu] = useState<{ x: number; y: number; messageId: string } | null>(null)
+
+  // Current conversation data
+  const currentConversation = conversations.find(c => c.id === currentConversationId)
+  const currentMessages = currentConversationId ? (messages[currentConversationId] || []) : []
+
+  // Find contact for conversation
+  const getConversationContact = (conv: Conversation): Contact | undefined => {
+    if (conv.is_group) return undefined
+    return contacts.find(c => conv.participant_ids.includes(c.id))
+  }
+
+  // Get sender name for group messages
+  const getSenderName = (senderId: string): string => {
+    if (senderId === 'self') return 'Du'
+    const contact = contacts.find(c => c.id === senderId)
+    return contact?.name?.split(' ')[0] || 'Unbekannt'
+  }
+
+  // Filter conversations by search
+  const filteredConversations = useMemo(() => {
+    if (!searchQuery) return recentConversations
+    const q = searchQuery.toLowerCase()
+    return recentConversations.filter(c =>
+      c.title?.toLowerCase().includes(q) ||
+      c.last_message?.toLowerCase().includes(q)
+    )
+  }, [recentConversations, searchQuery])
+
+  // Group messages by date
+  const groupedMessages = useMemo(() => {
+    const groups: { date: string; messages: Message[] }[] = []
+    let currentDate = ''
+
+    for (const msg of currentMessages) {
+      const msgDate = formatMessageDate(msg.timestamp)
+      if (msgDate !== currentDate) {
+        currentDate = msgDate
+        groups.push({ date: msgDate, messages: [] })
+      }
+      groups[groups.length - 1].messages.push(msg)
+    }
+
+    return groups
+  }, [currentMessages])
+
+  // Select conversation
+  const selectConversation = async (conv: Conversation) => {
+    setCurrentConversationId(conv.id)
+    if (conv.unread_count > 0) {
+      await markAsRead(conv.id)
+    }
+    setShowContactInfo(false)
+  }
+
+  // Send message
+  const handleSendMessage = async () => {
+    if (!messageInput.trim() || !currentConversationId) return
+
+    setIsSending(true)
+    await sendMessage(currentConversationId, messageInput.trim(), sendWithEmail)
+    setMessageInput('')
+    setIsSending(false)
+    setShowEmojiPicker(false)
+    setShowTemplates(false)
+  }
+
+  // Insert emoji
+  const handleEmojiSelect = (emoji: string) => {
+    setMessageInput(prev => prev + emoji)
+  }
+
+  // Start new conversation
+  const handleStartConversation = async (contact: Contact) => {
+    const conv = await createConversation(contact.id)
+    if (conv) {
+      setCurrentConversationId(conv.id)
+      setShowNewConversation(false)
+    }
+  }
+
+  // Handle context menu
+  const handleContextMenu = (e: React.MouseEvent, messageId: string) => {
+    e.preventDefault()
+    setContextMenu({ x: e.clientX, y: e.clientY, messageId })
+  }
+
+  // Close context menu on click outside
+  useEffect(() => {
+    const handleClick = () => setContextMenu(null)
+    if (contextMenu) {
+      document.addEventListener('click', handleClick)
+      return () => document.removeEventListener('click', handleClick)
+    }
+  }, [contextMenu])
+
+  const currentContact = currentConversation ? getConversationContact(currentConversation) : undefined
+
+  return {
+    // Context data
+    contacts, templates, unreadCount,
+    currentConversationId, currentConversation, currentContact,
+    filteredConversations, groupedMessages,
+    // UI state
+    messageInput, setMessageInput,
+    sendWithEmail, setSendWithEmail,
+    isSending,
+    showNewConversation, setShowNewConversation,
+    showEmojiPicker, setShowEmojiPicker,
+    showTemplates, setShowTemplates,
+    showContactInfo, setShowContactInfo,
+    searchQuery, setSearchQuery,
+    contextMenu, setContextMenu,
+    // Actions
+    selectConversation,
+    handleSendMessage,
+    handleEmojiSelect,
+    handleStartConversation,
+    handleContextMenu,
+    getSenderName,
+    getConversationContact,
+    // From context
+    pinConversation,
+    muteConversation,
+    deleteMessage,
+  }
+}