feat: make frontend fully responsive with mobile-first layout

Add mobile-responsive design with full feature parity:
- Bottom sheet (vaul) with 3 snap points for map+list coexistence
- Swipeable property cards with horizontal scroll-snap
- Hamburger menu with health, tasks, user info
- Full-screen map with repositioned legend (top-left on mobile)
- Filter FAB opening Sheet drawer
- TaskProgressDrawer from bottom on mobile
- All changes gated behind useIsMobile() hook (768px breakpoint)
- Desktop layout completely untouched

New components: MobileBottomSheet, SwipeableCardRow,
PropertyCardCompact, MobileMenu

Also fixes: idempotent longitude migration, React hooks order

frontend/src/index.css

@@ -145,3 +145,11 @@
 .animate-accordion-up {
   animation: accordion-up 0.2s ease-out;
 }
+
+@utility scrollbar-none {
+    -ms-overflow-style: none;
+    scrollbar-width: none;
+    &::-webkit-scrollbar {
+        display: none;
+    }
+}