Add MOT/insurance renewal hints, table service card, and favicon

- Renewal tracking: compute due/overdue status from the most recent
  mot/insurance event (renewal_months, renewal_due_soon_days settings),
  surfaced on the service card and dashboard.
- Service-status card metrics now render as a two-column label/value
  table with row separators instead of wrapping auto-fill grid cells.
- Add a bicycle favicon (favicon.svg) to base + login templates.

Co-Authored-By: opencode <opencode@users.noreply.github.com>

app/static/favicon.svg

@@ -0,0 +1,9 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="64" height="64">
+  <rect width="64" height="64" rx="14" fill="#4c8dff"/>
+  <g fill="none" stroke="#ffffff" stroke-width="3.4" stroke-linecap="round" stroke-linejoin="round">
+    <circle cx="18" cy="43" r="10"/>
+    <circle cx="46" cy="43" r="10"/>
+    <path d="M18 43 L31 43 M31 43 L26 24 M26 24 L45 24 M45 24 L46 43 M31 43 L45 24"/>
+    <path d="M45 24 L49 17 M22 24 L30 24"/>
+  </g>
+</svg>