Fix navbar brand icon display with flexbox alignment

Fixed Bootstrap Icon being cut off in navbar by adding proper flexbox
alignment and line-height controls to the brand link.

Changes:
- Add display: inline-flex to .rg-brand for proper icon alignment
- Add align-items: center to vertically center icon with text
- Add gap: 0.5rem for spacing between icon and text
- Set line-height: 1 to prevent extra vertical space
- Make icon slightly larger (1.75rem) for better visual hierarchy

This ensures the shield icon displays fully without being clipped.

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

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

app/views/layouts/application.html.erb

@@ -69,12 +69,21 @@
       font-weight: 700;
       color: var(--rg-primary);
       text-decoration: none;
+      display: inline-flex;
+      align-items: center;
+      gap: 0.5rem;
+      line-height: 1;
     }
 
     .rg-brand:hover {
       color: var(--rg-primary-dark);
     }
 
+    .rg-brand i {
+      font-size: 1.75rem;
+      line-height: 1;
+    }
+
     /* Modern Sidebar */
     .rg-sidebar {
       position: fixed;