feat: frame-based positioning and mark system foundation

Core Changes:
- Fix SearchView to use start_frame/end_frame directly (no time*fps conversion)
- Add hard_delete support to delete_trace API
- VideoPlayer: Main timeline + Mark system foundation
- Proxy: Add local routes for auth, media, identity-matches, cluster-results
- Add .gitignore to exclude build artifacts and dependencies

Design Documents:
- Multi-track Mark system design (.opencode/plans/)
- Video editing positioning standards research

Files Modified:
- src/views/SearchView.vue: Frame positioning, ensureMinDuration (240 frames)
- src/views/PeopleView.vue: batchDeleteGroups with hard_delete
- src/api/index.ts: delete_trace with hard_delete body
- src/components/VideoPlayer.vue: Timeline + Mark UI
- src-tauri/src/proxy.rs: New local routes
- AGENTS.md: Update documentation

src/router/index.ts

@@ -12,8 +12,8 @@ const routes: RouteRecordRaw[] = [
   { path: '/login', name: 'Login', component: LoginView },
   { path: '/search', name: 'Search', component: SearchView },
   { path: '/library', name: 'Library', component: LibraryView },
-  { path: '/people', name: 'People', component: PeopleView },
-  { path: '/people/:uuid', name: 'PersonDetail', component: PersonDetailView },
+  { path: '/face', name: 'Face', component: PeopleView },
+  { path: '/face/:uuid', name: 'FaceDetail', component: PersonDetailView },
   { path: '/admin', name: 'Admin', component: AdminView },
   { path: '/client', name: 'Client', component: ClientView }
 ]
@@ -23,4 +23,23 @@ const router = createRouter({
   routes
 })
 
+router.beforeEach((to, _from, next) => {
+  const token = localStorage.getItem('token')
+  const isLoggedIn = !!token
+  
+  if (to.path === '/login') {
+    if (isLoggedIn) {
+      next('/search')
+    } else {
+      next()
+    }
+  } else {
+    if (isLoggedIn) {
+      next()
+    } else {
+      next('/login')
+    }
+  }
+})
+
 export default router