feat(messages): unified conversation inbox — connect demand ↔ supply, offers reach the seeker

Phase 1 of the messaging rework: one conversation/thread model (Inquiry) is the single source of truth, read perspectivally by both sides.

- domain/inquiry: add kind (INQUIRY|OFFER), tenantOrgId (demand org), offeredPropertyIds
- provider/service: InquiryFilters gains tenantOrgId+kind; new createInquiry (demand→supply) & createOffer (supply→demand) materialize threads; addMessage bumps unread; reply carries senderType (tenant vs supply_user)
- hooks: useCreateInquiry, useCreateOffer; reply payload carries sender perspective
- demand: InquiryQuickDialog → createInquiry via provider (session-based tenant/org, no hardcode); Anfragen.tsx reads via React Query (tenantOrgId) with Gesendet/Erhalten tabs, replies via provider, shows offered properties for OFFER threads; inquiryStore reduced to dialog-only (removes Zustand server-data island)
- supply: OfferChatComposer send now materializes an OFFER conversation into the seeker's inbox (routed via latentNeed.tenantOrgId); Anfragencenter gains a "Gesendet" tab; ActiveInquiriesTab filters by perspective (org + kind)
- seed: merge demand inquiries with tenantOrgId=org-mobimo + 2 OFFER seeds; provider seeds from both sets

Closes the loop: a sent inquiry reaches the Verwaltung and a sent offer reaches the Nachfrager — both answerable in one thread.

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

src/hooks/useInquiries.ts

@@ -1,7 +1,7 @@
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
 import { inquiryService } from '../services/inquiryService'
-import type { InquiryFilters } from '../provider/IInquiryProvider'
-import type { Attachment } from '../domain/inquiry'
+import type { InquiryFilters, CreateInquiryInput, CreateOfferInput } from '../provider/IInquiryProvider'
+import type { Attachment, InquiryMessage } from '../domain/inquiry'
 import { useToastStore } from '../stores/toastStore'
 
 export function useActiveInquiries(filters?: InquiryFilters) {
@@ -29,7 +29,7 @@ export function useSendInquiryReply() {
       payload,
     }: {
       inquiryId: string
-      payload: { subject?: string; body: string; attachments?: Attachment[] }
+      payload: { subject?: string; body: string; attachments?: Attachment[]; senderType?: InquiryMessage['senderType']; senderName?: string }
     }) => inquiryService.sendInquiryReply(inquiryId, payload),
     onSuccess: (_data, { inquiryId }) => {
       qc.invalidateQueries({ queryKey: ['inquiry', inquiryId] })
@@ -41,6 +41,31 @@ export function useSendInquiryReply() {
   })
 }
 
+/** Demand→Supply: neue Anfrage erstellen (ersetzt die alte Zustand-Insel). */
+export function useCreateInquiry() {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: (input: CreateInquiryInput) => inquiryService.createInquiry(input),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ['inquiries'] })
+    },
+    onError: () => {
+      useToastStore.getState().showToast('Anfrage konnte nicht gesendet werden.', 'error')
+    },
+  })
+}
+
+/** Supply→Demand: Angebot als Konversation im Nachfrager-Postfach materialisieren. */
+export function useCreateOffer() {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: (input: CreateOfferInput) => inquiryService.createOffer(input),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ['inquiries'] })
+    },
+  })
+}
+
 export function useMarkThreadAsRead() {
   const qc = useQueryClient()
   return useMutation({