fix: resolve TypeScript compilation errors

Fixes:
- VideoPlayer.vue: restore allTags, filteredMarks, marksByTag (removed by mistake)
- PeopleView.vue: fix frameTime scope in playFaceDetailVideo catch block
- Both errors caused white screen on build failure

Root cause:
1. visibleTags duplicate declaration (old + new logic)
2. frameTime undefined in catch block (scope issue)

Solution:
1. Keep allTags/filteredMarks/marksByTag (needed in template)
2. Keep visibleTags (new logic for processor toggles)
3. Move frameTime calculation to correct scope in catch block

src/composables/useTheme.ts

@@ -0,0 +1,12 @@
+import { useDark, useToggle } from '@vueuse/core'
+
+export const isDark = useDark({
+  selector: 'html',
+  attribute: 'data-theme',
+  valueDark: 'dark',
+  valueLight: 'light',
+})
+
+export const toggleDark = () => {
+  isDark.value = !isDark.value
+}