feat: add nerve to stats bar, gym nav link, nerve dashboard card

- Add nerve chip to stats-bar showing current/max nerve with purple brain icon
- Add Gym link to sidebar navigation with muscle emoji and active state
- Add Nerve card to dashboard with progress bar, description, and Go to Gym link

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

resources/views/layouts/navigation.blade.php

@@ -25,6 +25,14 @@
                     <span>Inventory</span>
                 </a>
             </li>
+            <li>
+                <a href="{{ route('game.gym.index') }}"
+                   class="flex items-center space-x-3 px-3 py-2 rounded-lg text-sm transition
+                          {{ request()->routeIs('game.gym.*') ? 'border-l-2 border-crime-500 bg-syndicate-800 text-gray-100 pl-[10px]' : 'text-gray-400 hover:bg-syndicate-800 hover:text-gray-100' }}">
+                    <span class="text-base">💪</span>
+                    <span>Gym</span>
+                </a>
+            </li>
             <li>
                 <a href="{{ route('game.character.show') }}"
                    class="flex items-center space-x-3 px-3 py-2 rounded-lg text-sm transition