feat: dashcam photo mode with telemetry frame, lens drift and postcard capture

src/components/AppShell.vue

@@ -24,6 +24,7 @@ import { useMotionPreferences } from '@/composables/useMotionPreferences';
 import { useRouteMemory } from '@/composables/useRouteMemory';
 import { useRouteLog } from '@/composables/useRouteLog';
 import { useBillboard } from '@/composables/useBillboard';
+import { useDashcam } from '@/composables/useDashcam';
 import { assetUrl } from '@/content/asset-url';
 import { signRouteFor } from '@/journey/sign-routes';
 import { END_OF_SHIFT_SUBLINE } from '@/journey/dawn';
@@ -160,6 +161,16 @@ const headlight = useHeadlightBeam({
   quality: actualQuality,
   activeSectionId: () => journey.value.activeSectionId,
 });
+/* DASHCAM: a full-screen photo mode over the live scene (lazy frame). */
+const dashcam = useDashcam({
+  allowed: computed(() => controlsReady.value
+    && motion.policy.value.reason === 'full'
+    && motion.policy.value.allowSceneRequest
+    && actualQuality.value !== 'static'
+    && pageLifecycle.value === 'active'),
+  sceneRunning: computed(() => sceneState.value === 'running'),
+  drift: () => actualQuality.value !== 'low' && matchMedia('(pointer: fine)').matches,
+});
 const activeSectionLabel = computed(() => sectionLabel(journey.value.activeSectionId));
 const serverDefaultPolicy: MotionPolicy = {
   allowSceneRequest: false,
@@ -376,6 +387,7 @@ onUnmounted(() => removePageListeners());
     :audio-state="audio.state.value"
     :audio-muted="audio.muted.value"
     :audio-volume="controlsReady ? motion.volume.value : 0.4"
+    :dashcam="dashcam.available.value"
     @pause="pauseMotion"
     @resume="resumeMotion"
     @enable="enableMotion"
@@ -384,5 +396,17 @@ onUnmounted(() => removePageListeners());
     @audio-resume="audio.resumeFromGesture"
     @audio-mute-toggle="toggleAudioMuted"
     @audio-volume-change="updateAudioVolume"
+    @dashcam="dashcam.show"
+    @dashcam-prefetch="dashcam.prefetch"
+  />
+  <component
+    :is="dashcam.frame.value"
+    v-if="dashcam.open.value && dashcam.frame.value"
+    :journey="journey"
+    :section-label="activeSectionLabel"
+    :name="content.identity.name"
+    :city="content.identity.location.city"
+    :scene-ready="sceneState === 'running'"
+    @close="dashcam.close"
   />
 </template>