Make card borders lighter and add spacing between cards

- Change border color from brightNavy to navyBlue with 0.3 opacity (lighter)
- Reduce border width from 2px to 1.5px for subtler appearance
- Lighten shadow opacity from 0.18 to 0.12 for softer effect
- Reduce shadow blur from 24 to 20 and offset from 8 to 6
- Add 16px bottom margin between cards for proper spacing
- Maintain overall card design while making it more subtle

sojorn_app/lib/widgets/sojorn_post_card.dart

@@ -80,19 +80,20 @@ class sojornPostCard extends StatelessWidget {
         splashColor: AppTheme.queenPink.withOpacity(0.3),
         highlightColor: Colors.transparent,
         child: Container(
+          margin: const EdgeInsets.only(bottom: 16), // Add spacing between cards
           padding: _padding,
           decoration: BoxDecoration(
             color: AppTheme.cardSurface,
             borderRadius: BorderRadius.circular(20),
             border: Border.all(
-              color: AppTheme.brightNavy,
-              width: 2,
+              color: AppTheme.navyBlue.withValues(alpha: 0.3), // Lighter border
+              width: 1.5, // Slightly thinner border
             ),
             boxShadow: [
               BoxShadow(
-                color: AppTheme.brightNavy.withValues(alpha: 0.18),
-                blurRadius: 24,
-                offset: const Offset(0, 8),
+                color: AppTheme.brightNavy.withValues(alpha: 0.12), // Lighter shadow
+                blurRadius: 20,
+                offset: const Offset(0, 6),
               ),
             ],
           ),