feat: full responsive layout — mobile sidebar, stacked panels, fullscreen drawers

- AppShell: permanent sidebar on desktop, temporary drawer + hamburger on mobile (<md)
- TopBar: hamburger icon on mobile, AI-Assistent als Icon-Button auf kleinen Screens
- MatchDetail: Sidebar stacks below content on mobile, key facts wrap, px responsive
- Properties: Drawer fullscreen (100vw) on mobile, 650px on desktop
- ActiveInquiriesTab: mobile shows list → tap opens detail with back button
- LatentInquiriesTab: mobile sequential navigation (list → detail → own properties), tablet 2-col, desktop 3-col
- PublicNeedList: fullWidth prop for mobile layout
- InquiryDetailPanel: property card stacks below chat on mobile

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/anfragencenter/PublicNeedList.tsx

@@ -7,18 +7,19 @@ import { EmptyState } from '../ui'
 interface PublicNeedListProps {
   selectedNeedId: string | null
   onSelect: (id: string) => void
+  fullWidth?: boolean
 }
 
-export function PublicNeedList({ selectedNeedId, onSelect }: PublicNeedListProps) {
+export function PublicNeedList({ selectedNeedId, onSelect, fullWidth }: PublicNeedListProps) {
   const { data: needs = [], isLoading, error } = usePublicNeeds()
 
   return (
     <Box
       sx={{
-        width: 280,
-        minWidth: 280,
+        width: fullWidth ? '100%' : 280,
+        minWidth: fullWidth ? 'unset' : 280,
         flexShrink: 0,
-        borderRight: '1px solid #e2e8f0',
+        borderRight: fullWidth ? 'none' : '1px solid #e2e8f0',
         bgcolor: 'white',
         display: 'flex',
         flexDirection: 'column',