feat: Add collapsible sections and mobile grid layout

- Convert Active Sessions and Trusted Devices to collapsible Accordion components
- Display count badge in collapsed state
- Show loading state in accordion header
- Implement 2-card grid layout on mobile (xs=6)
- Responsive card sizing and spacing
- Centered layout on mobile, horizontal on desktop
- Hide full birthdate on mobile, show age only

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

maternal-web/components/settings/SessionsManagement.tsx

@@ -20,6 +20,9 @@ import {
   ListItemSecondaryAction,
   IconButton,
   Divider,
+  Accordion,
+  AccordionSummary,
+  AccordionDetails,
 } from '@mui/material';
 import {
   Devices,
@@ -28,6 +31,7 @@ import {
   Tablet,
   Delete,
   CheckCircle,
+  ExpandMore,
 } from '@mui/icons-material';
 import { sessionsApi, type SessionInfo } from '@/lib/api/sessions';
 import { motion } from 'framer-motion';
@@ -116,26 +120,41 @@ export function SessionsManagement() {
 
   if (isLoading) {
     return (
-      <Card>
-        <CardContent sx={{ display: 'flex', justifyContent: 'center', py: 4 }}>
-          <CircularProgress />
-        </CardContent>
-      </Card>
+      <Accordion>
+        <AccordionSummary expandIcon={<ExpandMore />}>
+          <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, width: '100%' }}>
+            <Devices color="primary" />
+            <Typography variant="h6" fontWeight="600">
+              Active Sessions
+            </Typography>
+            <CircularProgress size={20} sx={{ ml: 'auto' }} />
+          </Box>
+        </AccordionSummary>
+      </Accordion>
     );
   }
 
   return (
     <>
-      <Card>
-        <CardContent>
-          <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, mb: 2 }}>
+      <Accordion>
+        <AccordionSummary
+          expandIcon={<ExpandMore />}
+          sx={{
+            '& .MuiAccordionSummary-content': {
+              margin: '12px 0',
+            },
+          }}
+        >
+          <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, width: '100%' }}>
             <Devices color="primary" />
             <Typography variant="h6" fontWeight="600">
               Active Sessions
             </Typography>
-            <Chip label={`${sessions.length} active`} size="small" sx={{ ml: 'auto' }} />
+            <Chip label={`${sessions.length}`} size="small" sx={{ ml: 'auto', mr: 1 }} />
           </Box>
+        </AccordionSummary>
 
+        <AccordionDetails>
           <Typography variant="body2" color="text.secondary" sx={{ mb: 3 }}>
             Manage your active sessions across different devices. You can revoke access from any device.
           </Typography>
@@ -220,8 +239,8 @@ export function SessionsManagement() {
               )}
             </>
           )}
-        </CardContent>
-      </Card>
+        </AccordionDetails>
+      </Accordion>
 
       {/* Revoke Session Dialog */}
       <Dialog open={revokeDialogOpen} onClose={() => setRevokeDialogOpen(false)} maxWidth="sm" fullWidth>