feat: responsive layout + Reminder Manager redesign

- Auto-collapse sidebar at <1536px (all laptops), expand at ≥1536px
- Responsive drawer/panel widths across Pipeline, Properties, MyListings, Anfragen, MatchDetail, AISearch
- Reminder Manager: dot+label priority badge, Fläche column removed, status only for non-active rows
- ReminderKpiBar: focal Überfällig card, three secondary KPIs
- ReminderDetailDrawer: Task Panel redesign — Finanzen removed, Notiz promoted, Pre-Market as inline badge, full create form
- useCreateReminder hook wired to reminderService.create with cache invalidation
- Mock data: contract-derived reminders (LEASE_EXPIRY, BREAK_OPTION, RENT_REVIEW, INSURANCE_RENEWAL, SCHATTENMARKT_RELEASE) now show auto-creation note in Verlauf

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

src/pages/demand/Anfragen.tsx

@@ -134,8 +134,8 @@ export default function Anfragen() {
       {/* ── Left panel ── */}
       <Box
         sx={{
-          width: { xs: mobileShowChat ? 0 : '100%', md: 320 },
-          minWidth: { md: 320 },
+          width: { xs: mobileShowChat ? 0 : '100%', md: 280, lg: 300, xl: 320 },
+          minWidth: { md: 280, lg: 300, xl: 320 },
           flexShrink: 0,
           display: 'flex', flexDirection: 'column',
           borderRight: `1px solid ${DS_BORDER.default}`,