fix: Properties grid — wider min card width, more breathing room

Change minmax from 240px to 320px and gap from 1.5 to 2.5 so the
grid shows 3-4 columns instead of 9-10 on a wide screen.

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

src/pages/supply/Properties.tsx

@@ -191,7 +191,7 @@ export default function Properties() {
 
       <Box sx={{ flex: 1, overflowY: 'auto' }}>
         {view === 'grid' ? (
-          <Box sx={{ display: 'grid', gridTemplateColumns: 'repeat(auto-fill, minmax(240px, 1fr))', gap: 1.5, p: 1.5 }}>
+          <Box sx={{ display: 'grid', gridTemplateColumns: 'repeat(auto-fill, minmax(320px, 1fr))', gap: 2, p: 2.5 }}>
             {filtered.map(p => (
               <PropertyIntelligenceCard key={p.id} property={p} onSelect={setSelectedId} />
             ))}