fix(contacts): Fix Pending Contacts list height

Problem: #pendingList had max-height: 200px showing only 1-2 contacts
with huge unused whitespace below.

Solution:
- Desktop: height calc(100vh - 280px) - slightly more than existingList
  due to extra description text
- Mobile: height calc(100vh - 320px) - adjusted for mobile layout
- Changed from max-height to height for consistent behavior
- Added min-height: 300px for safety

Now pending contacts list properly utilizes available screen space.

app/templates/contacts_base.html

@@ -172,10 +172,11 @@
 
         /* Scrollable contacts lists */
         #pendingList {
-            max-height: 200px;
+            height: calc(100vh - 280px);
             overflow-y: auto;
             overflow-x: hidden;
             -webkit-overflow-scrolling: touch;
+            min-height: 300px;
         }
 
         #existingList {
@@ -331,6 +332,10 @@
                 height: calc(100vh - 300px);
             }
 
+            #pendingList {
+                height: calc(100vh - 320px);
+            }
+
             .contacts-list-fullscreen {
                 height: calc(100vh - 300px);
             }