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/pages/supply/Anfragencenter.tsx

@@ -2,11 +2,13 @@ import { useState } from 'react'
 import { useLocation } from 'react-router'
 import { Box, Tab, Tabs, Typography } from '@mui/material'
 import { ActiveInquiriesTab, LatentInquiriesTab, OfferWizard } from '../../components/anfragencenter'
+import { useSessionStore } from '../../stores/sessionStore'
 
 export default function Anfragencenter() {
   const location = useLocation()
   const initialTab = (location.state as { tab?: number } | null)?.tab ?? 0
   const [tab, setTab] = useState(initialTab)
+  const orgId = useSessionStore(s => s.currentUser?.organizationId)
   return (
     <Box sx={{ display: 'flex', flexDirection: 'column', height: '100%', overflow: 'hidden' }}>
       <Box sx={{ borderBottom: '1px solid #e8e7e4', px: 3, bgcolor: 'white', flexShrink: 0 }}>
@@ -21,12 +23,20 @@ export default function Anfragencenter() {
           }}
         >
           <Tab label="Aktive Anfragen" />
+          <Tab label="Gesendet" />
           <Tab label="Latente Anfragen" />
         </Tabs>
       </Box>
       <Box sx={{ flex: 1, overflow: 'hidden' }}>
-        {tab === 0 && <ActiveInquiriesTab />}
-        {tab === 1 && <LatentInquiriesTab />}
+        {tab === 0 && <ActiveInquiriesTab filters={{ organizationId: orgId, kind: 'INQUIRY' }} />}
+        {tab === 1 && (
+          <ActiveInquiriesTab
+            filters={{ organizationId: orgId, kind: 'OFFER' }}
+            emptyTitle="Keine gesendeten Angebote"
+            emptyDescription="Angebote, die Sie aus „Latente Anfragen" versenden, erscheinen hier."
+          />
+        )}
+        {tab === 2 && <LatentInquiriesTab />}
       </Box>
       <OfferWizard />
     </Box>