feat: GripAnalysisView — car grip envelope visualization

- New GripAnalysisView with 4 scatter charts:
  1. Grip Envelope (peak G vs speed: lateral/accel/brake)
  2. Grip Circle (longitudinal vs lateral G scatter)
  3. Cornering Grip vs Speed
  4. Steering Response (steer angle vs lateral G)
- Summary stats: max lateral/accel/brake/combined G, peak lateral speed
- GripAnalysis types + type guard
- car_grip use case in SessionDetailView (quick stats + view button)
- Route /analysis/grip/:id
- Global .grid-4 CSS utility

src/views/SessionDetailView.vue

@@ -2,8 +2,8 @@
 import { ref, onMounted, computed } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useSessionsStore } from '@/stores/sessions'
-import type { ShiftPointAnalysis, TrackMapAnalysis } from '@/types'
-import { isShiftPointAnalysis, isTrackMapAnalysis } from '@/utils/analysis'
+import type { ShiftPointAnalysis, CarGripAnalysis, TrackMapAnalysis } from '@/types'
+import { isShiftPointAnalysis, isCarGripAnalysis, isTrackMapAnalysis } from '@/utils/analysis'
 import * as api from '@/api/client'
 
 const props = defineProps<{
@@ -56,6 +56,14 @@ const trackAnalysis = computed((): TrackMapAnalysis | null => {
   return null
 })
 
+const gripAnalysis = computed((): CarGripAnalysis | null => {
+  if (!analysisData.value) return null
+  if (isCarGripAnalysis(analysisData.value)) {
+    return analysisData.value
+  }
+  return null
+})
+
 onMounted(async () => {
   await store.fetchSession(sessionId.value)
 })
@@ -101,6 +109,8 @@ function viewAnalysis() {
   if (!session.value) return
   if (session.value.use_case === 'shift_points') {
     router.push({ name: 'shift-points', params: { id: session.value.id } })
+  } else if (session.value.use_case === 'car_grip') {
+    router.push({ name: 'grip-analysis', params: { id: session.value.id } })
   }
 }
 
@@ -339,8 +349,28 @@ async function handleBuildTrack() {
             </div>
           </div>
 
+          <!-- Quick stats for car grip -->
+          <div v-if="gripAnalysis" class="analysis-stats grid grid-4 mb-2">
+            <div class="stat-card">
+              <span class="stat-label">Max Lateral G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_lateral_g.toFixed(2) }}</span>
+            </div>
+            <div class="stat-card">
+              <span class="stat-label">Max Accel G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_accel_g.toFixed(2) }}</span>
+            </div>
+            <div class="stat-card">
+              <span class="stat-label">Max Brake G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_brake_g.toFixed(2) }}</span>
+            </div>
+            <div class="stat-card">
+              <span class="stat-label">Max Combined G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_combined_g.toFixed(2) }}</span>
+            </div>
+          </div>
+
           <div class="flex gap-2">
-            <button v-if="session.use_case === 'shift_points'" class="btn btn-primary" @click="viewAnalysis">
+            <button v-if="session.use_case === 'shift_points' || session.use_case === 'car_grip'" class="btn btn-primary" @click="viewAnalysis">
               📊 View Full Analysis
             </button>
             <button class="btn btn-secondary" @click="handleReAnalyze">