feat(dashboard): 3-col layout with Overview stats, speed chart fixes

- base.html: fix notification badge positioning (inline style, no overflow
  clip); remove py-4 from main; update footer text
- index.html: split bottom row into 3 cols (GPS / Overview / Speed);
  Overview card with 6 live stats from /api/stats; speed chart auto-expands
  on desktop; shown.bs.collapse triggers speedChart.resize()

Co-authored-by: Copilot <[email protected]>

templates/base.html

@@ -68,7 +68,7 @@
                         <button class="btn btn-link position-relative p-2" id="alert-toggle" type="button"
                                 data-bs-toggle="dropdown" aria-expanded="false" aria-label="System alerts">
                             <i class="fas fa-bell fa-fw text-secondary"></i>
-                            <span id="alert-count" class="position-absolute top-0 start-100 translate-middle badge rounded-pill bg-danger" hidden></span>
+                            <span id="alert-count" class="position-absolute badge rounded-pill bg-danger" style="top:2px;right:2px;font-size:.6rem;min-width:1.1em;padding:.2em .35em;" hidden></span>
                         </button>
                         <div class="dropdown-menu dropdown-menu-end shadow" id="alert-menu" aria-labelledby="alert-toggle">
                             <h6 class="dropdown-header">System alerts</h6>
@@ -84,12 +84,12 @@
             </div>
         </nav>
 
-        <main class="container-fluid py-4 px-3 px-md-4 main-content">
+        <main class="container-fluid px-3 px-md-4 main-content">
             {% block content %}{% endblock %}
         </main>
 
         <footer class="bg-white border-top text-center py-3 small text-muted d-none d-md-block">
-            &copy; Yaris OBD {{ car.model }}
+            &copy; vroom vroom yaris de course 2023
         </footer>
     </div>